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Lists the research papers to be published in the succeeding issues of the "European Journal of Biochemistry." "The structure of DNA junctions and their interaction with enzymes," by D.R. Duckett and colleagues; "CD4 gene transcription is transiently repressed during differentiation of myeloid cells to macrophage-like cells," by F.X. Pimentel-Muiñoz and colleagues; "Malonate decarboxylase of Malonomas rubra: a novel type of biotin-containing acetyl-enzyme," by H. Hilbi and colleagues.

Introduces the research papers to be published in the "European Journal of Biochemistry," succeeding the May 15, 1985. "Primer-independent abortive initiation by wheat-germ RNA polymerase B," by H. Mosig et al; "Protein structure and gene organization of mouse lactate dehydrogenase-A isozyme," S.S.-L. Li et al; "A model for intracellular complexation between gene-5 protein and bacteriophage fd DNA," by G.D. Bayer et al.

This article presents titles of forthcoming research papers related to biochemistry. Some of the titles include "Solubilization and Partial Characterization of a Multienzyme Complex of DNA Synthesis From Human Lymphoblastoid Cells"; "Nucleotide Sequence of Cloned cDNA Coding for Mouse Casein"; "Effects of Acetylation on the Binding of N-Terminal Peptides of Histone H4 to DNA."

The article presents the list of research papers related to biochemistry, that will be published in forthcoming issues of the "European journal of Biochemistry." Some of these papers are--'A novel testis-specific 105-kDa protein related to 90-kDa heatshock protein,' by H. Itoh and Y. Tashima, 'Casein kinase II phosphorylates DNA-polymerase-a-DNA-primase without affecting its basic enzymic properties,' by V. Podust, G. Bialek, H. Stembach and F. Grosse, 'Structural and functional aspects of calcium homeostasis in eukaryotic cells,' by D. Pietrobon, F. di Virgilio and T. Pozzan.

This article presents a list of some of the forthcoming papers in biochemistry to be published in this journal. Some of the papers listed are "The Organization of the Chloroplast DNA in wheat and maize in the region containing the LS Gene," by B. Koller, H. Delius and T.A. Dyer, "Effect of Carbamination on the Buffering Power of Purified Human Hamoglobins A Solutions At Two Temperatures," by M. Castaing, E. Bursaux and C. Poyart, "The Complete Nucleotide of the Chicken Ovotransferrin mRNA," by J.M. Jeltsch and P. Chambon, "The Primary Structure of Hen Ovotransferrin," by J. Williams, T.C. Elleman, I.B. Kington, A.G. Wilkins and K.A. Kuhn.

The article presents the forthcoming papers that will be published in the "European Journal of Biochemistry." Some of these articles to be published are "Purification and Characterization of Thermus Caldophilus GK24 DNA Polymerase," by J.H. Park, J.S. Kim, S.-T. Kwon and D.-S. Lee, "Lactotransferrin Binding to Its Platelet Receptor Inhibits Platelet Aggregation," by B. Leveugle, J. Mazurier, D. Legrand, C. Mazurier, J. Montreuil and G. Spik and "Does Escherichia Coli Possess a Second Critrate Synthase Gene?," by A.J. Patton, D.W. Hough, P. Towner and M.J. Danson.

Lists articles to be published in the "European Journal of Biochemistry." Cloning and sequencing of mammalian glutathione reductase cDNA; Conformation of single-stranded nucleic acids; Characteristics of type VIII collagen; Salmon calcitonin.

A hybridization probe was used to study the regulation of expression of the gene coding for the small subunit of ribulose 1,5-bisphosphate carboxylase, during functional differentiation of protoplasts. A library of cDNA from poly(A)-containing RNA extracted from specially treated tobacco leaves was constructed in the plasmid pBR322, by blunt-end ligation. This library was screened by colony hybridization with 32P-labelled cDNA prepared from rnRNA coding for the precursor of the small subunit. A positive colony was identified containing recombinant plasmids with a nucleotide sequence homologous to this mRNA. These plasmids, bound to diazobenzyloxymethylated cellulose paper. were then used as a hybridization probe. The results showed unambiguously that the small subunit was not transcribed in protoplasts but was transcribed in undifferentiated white and chiorophylle containing green callus cultures derived from protoplasts. The discrepancy between these results and those obtained with classical techniques is discussed. [ABSTRACT FROM AUTHOR]

The nucleotide sequence of the simian virus 40 DNA segment that lies between the HindlII restriction endonuclease cleavage site at map position 0.324 and the AtuI cleavage site al 0.261 has been determined by the base-specific partial chemical degradation procedure of Maxam and Gilbert. This region comprises 335 base pairs and represents 6.4% of the total SV40 genome and 41% of the restriction fragment Hind-B. It connects in the clockwise direction to the restriction fragment Hind-I (described in the preceding paper). Hind-B is situated in the second half of the early transcription region of the SV40 genome and encodes information (including the termination signal) for the early protein large-T antigen. In the part of Hind-B described here, the DNA strand that has the same polarity as early 19-S mRNA defines only one open reading frame for translation; the other two are blocked by multiple triplets corresponding to termination codons. The open reading frame is part of one that runs throughout much of the early region: from the second splicing boundary of the large-T gene (position 0.534) to the information for the large-T stop signal (position 0.174) near the Hind-B/Hind-G junction, and which together with the non-contiguous DNA segment from position 0.65 (site of the information for the large-T start signal) to 0.60 (the first splicing boundary) codes for the entire large-T antigen. [ABSTRACT FROM AUTHOR]

An 11450-base DNA fragment containing the gene for the extracellular active-site serine DD-peptidase of Streptornyces R61 was cloned in Streptornyces lividans using the high-copy-number plasmid pi J702 as vector. Amplified expression of the excreted enzyme was observed. Producing clones were identified with the help of a specific antiserum directed against the pure DD-peptidase. The coding sequence of the gene was then located by hybridization with a specific nucleotide probe and sub-fragments were obtained from which the nucleotide sequence of the structural gene and the putative promoter and terminator regions were determined. The sequence suggests that the gene codes for a 406-amino-acid protein precursor. When compared with the excreted, mature DDpeptidase, this precursor possesses a cleavable 31-amino-acid N-terminal extension which has the characteristics of a signal peptide, and a cleavable 26-amino-acid C-terminal extension. On the basis of the data of Joris et al. (following paper in this journal), the open reading frame coding for the synthesis of the DD-peptidase was established. Comparison of the primary structure of the Streptomyces R61 DD-peptidase with those of several active-site serine β-lactamases and penicillin-binding proteins of Escherichia coli shows homology in those sequences that comprise the active-site serine residue. When the comparison is broadened to the complete amino acid sequences, significant homology is observed only for the pair Streptomyces R61 DD-peptidase/Escherichia coil ampC β-lactamase (class C). Since the Streptomyces R61 DD-peptidase and β-lactamases of class A have very similar three-dimensional structures [Kelly et al. (1986) Science (Wash. DC) 231, 1429-1431; Samraoui et al. (1986) Nature (Lond.) 320, 378-380], it is concluded that these tertiary features are probably also shared by the β-1actamases of class C, i.e. that the Streptomyces R61 DD-peptidase and the β-lactamases of classes A and C are related in an evolutionary sense. [ABSTRACT FROM AUTHOR]

The DNA-stimulated 75 000-Mr ATPase described in the preceding paper is shown to be a further catalytic DNA unwinding principle (DNA unwinding enzyme II) made in Escherichia coli cells (the first being the 180 000-Mr ATPase of the cells: DNA unwinding enzyme I). Unwinding depends, strictly, on the supply of ATP. It occurs only under conditions permitting ATP dephosphorylation and it proceeds as long as enzyme molecules are permitted to enter the enzyme · DNA complex. The enzyme binds specifically to single-stranded DNA yielding a complex of only limited stability. These results are interpreted in terms of a distributive mode of action of the enzyme. It is argued that chain separation starts near a single-stranded DNA region and that, forced by continued adsorption of enzyme molecules to the DNA, it develops along the duplex. This mechanism is different from that deduced previously for DNA unwinding enzyme I. Complicated results were obtained using ATPase prepared from rep3 mutant cells. [ABSTRACT FROM AUTHOR]

This paper presents the results of a systematic study on the effects of substituents on the base and sequence specificity of tricyclic heteroaromatic compounds interacting with DNA by intercalation. All the compounds tested are derived from proflavine and acridine orange analogs with different heteroatoms in the middle ring. Their base and sequence specificities were determined by differential dialysis of the ligand against DNA samples of differing G · C content. The main results indicate that (a) the introduction of a phenyl substituent into one of the two available positions of the middle ring increases or decreases the G · C specificity of the ligand depending on the position where the substitution takes place; (b) compounds of the substitution type of neutral red (2-methyl-3-amino-7-dimethyl-amino-phenazine) show unexpectedly high G · C specificities and (c) DNA ligands of pronounced sequence specificity for adjacent G · C pairs can be constructed by combining the structural elements of neutral red with an additional phenyl residue in the same molecule. The further study of compounds related to the phenylated neutral red revealed that the G · C specificity can be improved or destroyed by additional substituents. The comparison of the G · C specificity and the DNA-affinity data of the compounds studied leads to the suggestion that the specificity arises mainly from electronic factors which are strongly controlled through steric constraints on possible complex geometries. As a basis for the discussion a possible structure for the DNA complex of the phenylated neutral red is considered in which the extra phenyl ring at N-5 of the phenazinium system, protrudes into the large groove of the DNA helix while the tricyclic part of the ligand is inserted between the DNA base-pairs. [ABSTRACT FROM AUTHOR]

We extend the analysis of unbranched chains (preceding paper) to large parameter changes in branched systems using linear kinetic assumptions. More complex relationships between flux control coefficients and deviation indices are established. In particular, the deviation index in such systems depends on more than one control coefficient as well as on the magnitude of the enzyme change. Non-additivity of the indices is the general rule. Combined changes of groups of enzymes, whether co-ordinate or not, have also been formulated. Control coefficients can be estimated from a small number of independent large-change experiments. Alternatively, the amplification factors can be calculated given the knowledge of the control coefficients. A 'case study' using published data is presented. The movement of intermediate metabolites as a consequence of large parameter changes can be dealt with in a similar manner. Experimental methods for showing the admissibility of assuming the simplifying assumptions used are summarised. Some simulation studies show possible limits of the application of the approach and some aspects of the general, non-linear, case are discussed. It is concluded that, although metabolic systems are in principle non-linear, many behave, in practice, as quasi-linear systems. The relationships established between deviation indices and control coefficients therefore provide a practical way of predicting the effects of large-scale changes in parameters for many metabolic systems. [ABSTRACT FROM AUTHOR]

The physical map of 2C DNA (cf. following paper in this journal) was compared to the maps of SP0t, SP82 and Φe (three other Bacillus subtilis phages containing hydroxymethyluracil in place of thymine in their DNA). The overall organization of the four genomes was remarkably similar, as indicated by the topology of HaeIII and Sa/J cleavage segments. The proof was gathered for the presence in the four phage DNAs of large redundant ends carrying a single HaeIII recognition site. The location of the latter proved identical for 2C and SP01, but was shifted in the DNAs of SP 82 and Φe. Since the redundant end components of these hydroxymetbyluracil genomes are colinear, as shown by crossahybridization studies, the shifting of the HaeIII cleavage site is presumably due to two base substitutions, suppressing an endonuclease recognition site and establishing a new site elsewhere. Relatedness between the genomes of this family of viruses was evaluated from the fraction of conserved restriction fragments. According to these calculations. 6% base substitutions have occurred within the four viral DNAs, in the course of evolution. However, specific segments of 2 C DNA were not present in SP01 and Φe DNA, as shown by cross- hybridization with restriction fragments. These data indicate the occurrence of deletions, in addition to base substitutions, as evolutionary mechanisms prevailing in the genomes of this family of phages. [ABSTRACT FROM AUTHOR]

We report here the nucleotide sequence of the simian virus 40 DNA region that lies between the EcoRII restriction endonuclease cleavage sites at map positions 0.214 and 0.281. The sequence was determined by partial chemical degradation of terminally labeled DNA fragments according to the procedure of Maxam and Gilbert. This region represents 6.7% of the SV 40 genome and is located in the middle of HindII + III restriction fragment B. It is expressed as part of the early 19-S messenger RNA, which codes for the large-T antigen protein. Only one open reading frame for translation can be deduced from the message strand of the DNA and this reading frame connects in phase with the one of both neighboring fragments. This publication is the last in a series of papers about the T-antigen gene, and several properties of this gene and its product are discussed. The non-randomness of codon usage is similar to that previously discussed for the late part of the genome. Moreover, it appears that the choice of a third letter can be determined by the nature of the following codon; some codons which start with a pyrimidine are almost never preceded by an adenosine and some ANN-type codons are almost never preceded by a guanosine. [ABSTRACT FROM AUTHOR]

The effects of microtubule-associated protein binding to DNA on microtubule assembly in vitro were studied by turbidity measurements and electron microscopy. DNA inhibited microtubule assembly in a concentration-dependent manner. At DNA concentrations low enough to allow some polymerisation to occur, assembled microtubules were longer than those formed in the absence, indicating a reduction in the number of microtubule-associated proteins available for polymerisation. Also, by binding microtubule-associated proteins, DNA raised the critical con- centration of microtubule protein necessary for microtubule assembly. However, satellite DNA, which bound microtubule-associated proteins more effectively than bulk DNA, raised the critical concentration less. Similar effects were observed for the synthetic DNA polymers poly(dA) · poly(dT) and poly(dA-dT) · poly(dA-dT) compared to poly(dG) · poly(dC) and poly(dG-dC) · poly(dG-dC). Nitrocellulose filter binding assays showed that only microtubule-associated protein fractions which contained high-molecular-weight components exhibited DNA binding specifity. These high- molecular-weight polypeptides bound preferentially to eukariotic DNA as compared to phage DNA; fractions containing tau protein bound equally well to both DNA species. High-molecular-weight polypeptides also showed preferential binding to poly(dA-dT) · poly(dA-dT) compared to poly(dG-dC) · poly(dG-dC) synthetic DNA polymers. We suggest that satellite DNA acts in vivo as an initiation site for microtubule formation and that high-molecular-weight polypeptides could be the linker components of the kinetochore. [ABSTRACT FROM AUTHOR]

We have analysed limit digests of mini-circles from kinetoplast DNA of Crithidia luciliae by gel electrophoresis. Endonucleases HapII and AluI cut the circles into at least 37 and 21 fragments, respectively, and leave no circles intact. In both cases the added molecular weights of the fragments, estimated from mobility in gets, exceeds 18 × 106, i.e. more than 12 times the molecular weight of the mini-circle DNA. Endonucleases HindII + III, EcoRI and HpaI cut only part of the circles. These results show that the mini-circles are heterogeneous in base sequence. Different sequence classes are present in different amounts. DNA-DNA renaturation analysis of mini-circle DNA yields a complexity of about 3 × 106, i.e. twice the molecular weight of one mini-circle. The &Deltm of native and renatured duplexes is about 1°C, showing that the sequence heterogeneity is a micro-heterogeneity. Electron microscopy, get electrophoresis and sedimentation analysis show that the circles that are not cut by endonucleases HindII + III remain catenated in very large associations. These associations lack the ‘rosette’ structures and the long edge loops characteristic of intact kinetoptast DNA. This suggests that the mini-circle classes cut by endonucleases HindII + III are present throughout the network and that the maxi-circle component of the network (see accompanying paper) is not essential to hold the network together: Prolonged electrophoresis on 1.5% or 2% agarose gels resolves the open mini-circles into three and linearized mini-circles into four bands, present in different amounts. We conclude that the mini-circles are also heterogeneous in size, the difference in size between the two extreme size classes being 4% of the contour length. Digestion with endonuclease HapII shows that at least three out of these four bands differ in sequence, Possible mechanisms that could account for the micro-heterogeneity in sequence of mini-circles are discussed. [ABSTRACT FROM AUTHOR]

Among various molecular mechanisms of cell resistance to antitumor agents such as cisplatin, it has recently been suggested that enhanced DNA-repair activity might be involved in the resistant phenotype of cell lines. Mouse leukemia-cisplatin-resistant cell lines L1210/10 (adapted in vitro) and L1210/DDP (adapted in vivo) have been reported to exhibit an increase DNA-repair activity, as determined by host-cell reactivation after transformation with damaged plasmids. In this paper, excision-repair activity was monitored by an in-vitro assay allowing quantification of DNA-repair synthesis in cell extracts from resistant and sensitive parental cells (L1210/10 versus L1210/0 and L1210/DDP versus L1210/S). Experimental conditions for optimal repair-synthesis activity were found to be different from these reported with human cell-line extracts. L1210/S sensitive cell line, grown in vivo by a weekly intraperitoneal graft in mice, displayed a repair activity about fourfold lower than the same cell line maintained in vitro or than L1210/0 cell grown in vitro. The repair activity was found similar in a L1210/10 and L1210/0 cell lines, but it was enhanced in L1210/DDP resistant cell line when compared with its parental line. [ABSTRACT FROM AUTHOR]

Treatment of Ehrlich ascites tumor cells with 2-difluoromethylornithine (F2MeOrn), an enzyme-activated irreversible inhibitor of ornithine decarboxylase, resulted in depleted putrescine and spermidine content, and reduced growth rate. We have previously shown that adenine ribonucleotide levels are substantially increased in these polyamine-depleted cells. The present paper addresses the question whether the elevated ATP pool is accompanied by a concomitant increase in the dATP pool. if this is the case, the observed growth inhibition could be explained by the well-known dATP-mediated feedback inhibition of ribonucleotide reductase. We found that dNTP pools were not unbalanced and that dNTP synthesis was not arrested in polyamine-depleted cells. Moreover, the dNTP content and the activity of ribonucleotide reductase (CDP reduction) and thymidylate synthase, remained elevated despite the fact that the cells were inhibited in their growth by F2MeOrn treatment. Incorporation of a radiolabeled precursor into DNA was initially lower in F2MeOrn-treated cells than in control cells. However, while incorporation of a radiolabeled precursor into DNA decreased markedly in plateau-phase control cells, it remained at a higher level in cells inhibited in growth by polyamine depletion. This discrepancy may be explained by the fact that polyamine-depleted cells accumulated in the S phase, and that they had an increased content of acid-soluble radiolabeled DNA precursor. Our data indicate that polyamine depletion adversely affects the DNA synthetic machinery by reducing the rate of elongation. [ABSTRACT FROM AUTHOR]

The simian virus 40 (SV40) enhancer contains three 8-bp purine-pyrimidine alternating sequences which are known to adopt the left-handed Z-DNA conformation in vitro. In this paper, we have undertaken the determination of the DNA conformation adopted by these Z-motifs in the SV40 minichromosome. We have analyzed the presence of Z-DNA through the change in linkage which should accompany formation of this left-handed conformation. Our results indicate that, regardless of the precise moment of the viral lytic cycle at which minichromosomes are harvested and the condition of the transfected DNA, either relaxed or negatively supercoiled, none of the three Z motifs of the SV40 enhancer exist to a significant extent as Z-DNA in SV40 minichromosomes. The SV40 enhancer adopts predominantly a right-handed B-DNA conformation in vivo. [ABSTRACT FROM AUTHOR]

A 1.4-kb Pstl - HpaI DNA fragment carrying the Kiebsiella pneumoniae nifM gene has been sequenced; nifM has been shown to encode a 30.64Da polypeptide. Two other open-reading frames were identified upstream of nifM. The one immediately upstream of nziM encodes a 16.6-kDa polypeptide which has been identified by in vitro transcription/translation in an Escherichia coli 30000 × g supernatant system; we propose to designate this gene njfM. The sequence of the second open reading frame is incomplete but it does not correspond to nifV, the gene previously thought to be immediately upstream of nifM, and may therefore identify another new nif gene. Both nifM and nifM have functional n?f promoters with the characteristic -24, .42 consensus sequence, we find no evidence for a nifM upstream activator sequence. The role of nifZ in nitrogenase biosynthesis is unknown but its identification calls into question previous assertions that only nifM and nifH are required for the synthesis of nitrogenase Fe protein. [ABSTRACT FROM AUTHOR]

As shown in a previous paper[i. i. Lawrence et al. (1980) Eur. J. Biochem. 107, 263 -269], covalent spin labeling of basis residues in histone H I allows the study of the interaction of this protein with DNA. Using a step gradient dialysis procedure to reconstitute chromatin from labeled HI and stripped chromatin, it is shown that the process of interaction of the lysine residues and DNA is the same whether histone HI is bound to linear purified DNA or to HI- depleted chromatin. In contrast, spin labeling of the unique tyrosine of histone H 1 located in the globular part of the molecule shows that this part is more involved in the interaction with chromatin than it is with linear DNA (as judged from the lengthening of the rotational correlation time). These data are interpreted as reflecting different roles for the N and C termini of the molecule of H 1 and the central globular part. A model, based on these observations together with examination of the primary structures of histones HI, is proposed which accounts for the HI involvement in the chromatosome structure. [ABSTRACT FROM AUTHOR]

Polymorphism and microheterogeneity of DNA appear today as being capable of having important biological consequences. This paper presents a synthetic view of two major properties of the main known forms of DNA (A, B, alternating B, C, D and Z), namely their molecular electrostatic potentials and steric accessibilities. Variations in these properties are explained in terms of the conformational changes involved and deductions are drawn concerning their influence on the interactive properties of DNA with external agents. [ABSTRACT FROM AUTHOR]

Hybridization studies have indicated that on the M13 genome there are located regions which are transcribed in vivo with a high as well as with a low frequency. The region with the highest transcriptional activity coincides with the region coding for the polypeptides which during the infection cycle are needed most abundantly (gene V and gene VIII protein). The hybridization studies furthermore have indicated that at least a number of the promoters previously detected in vitro are operative in the infected cell. In addition the experimental data are consistent with the presence of three transcription termination signals on the M13 genome. With the aid of analytical and preparative hybridization studies we have been able to establish that during the infection cycle at least eleven M13-specific RNA species are made which range in size from 280 to 2000 nucleotides. The six major RNA species (i.e. an 8-S RNA with 370 nucleotides, a 9-S with 420, three 11-S species with 760, 810 and 860 nucleotides and a 14- species with 1140 nucleotides) are encoded by the region with the highest transcriptional activity (located between the N-terminal end of gene X and the C-terminal end of gene VIII). Characterization of these RNA species with respect to their genetic origin, codogenic properties and nucleotide sequences has indicated that their synthesis is terminated at the previously detected rho-independent transcription termination signal T0.25, which is located immediately after gene VIII. From the data obtained it furthermore could be deduced that the 5ʹ termini of these RNA .species are located as follows: for the 8-S RNA immediately in front of gene IX (promoter G0.18), the 9-S RNA within or immediately distal to the 5ʹ end of gene VII, the three 11-S RNAs within the C-terminal end of gene X and the 14-S RNA immediately in front of gene X. Analyses of the 5ʹ ends of the major RNA chains synthesized in vivo have indicated that four (i.e. the 9-S and three 11-S species) out of the six RNA species are the result of processing of precursor molecules. For this processing the RNA processing enzymes RNase III, RNase E, and RNase P are not required. The meaning of these results, in terms of the mechanisms by which the expression of the M13 genome is regulated, is discussed. [ABSTRACT FROM AUTHOR]

The complete nucleotide sequence of the 16-S RNA from Escherichia coli has been determined using rapid RNA-sequencing gel methods. The experimental data are fully described in this paper. The specificities of the ribonucleases, especially the ribonuclease PhyI are discussed and the consequences of the persistence of stable secondary structure are considered. The proposed sequence contains 1541 nucleotides and agrees completely with the DNA sequence of the rrnB cistron deduced by Brosius, J., Palmer, M. L., Kennedy, P.J., and Noller, H. F. [Proc. Natl Acad. Sci. U.S.A. (1978) 75, 4801–4805]. But there are several cistron heterogeneities of which we described 16 single-base heterogeneities, 7 of the deletion/insertion type and 9 of the transition or transversion type. Our observations suggest the existence, among the 7 ribosome RNA cistrons, of one or two mutated ones. The respective advantages and disadvantages of both RNA and DNA sequencing methods are discussed. [ABSTRACT FROM AUTHOR]

In this paper evidence is provided that one of the protein components of the water-soluble fraction of the call lens binds specifically to deoxyribonuclease I (DNAse I). On the basis of this property, the polypeptide could be purified by applying DNAse I affinity chromatography. Concomitantly a protein of Mr 55000 and a rather large amount of α-crystallin copurify with this polypeptide, which has a molecular weight of 42000. Highly purified 42000-Mr protein was also obtained by extraction of the water-insoluble fraction of the calf lens with 2-{(tris(hydroxyniethyl)methyl]amino}ethanesulfonic acid followed by gel filtration. Amino acid analyses, peptide mapping and electron microscopy show that the protein obtained from both lens fractions is identical to non-muscle actin. Furthermore the amino acid composition of the 55 000-Mr protein is identical to hog stomach skeletin and very similar to calf brain desmin. [ABSTRACT FROM AUTHOR]

The transcriptional origin of the polyadenylated RNA has been studied in dark-grown cultures of Euglena gracilis and during light-induced chloroplast development. Complementary DNA (eDNA) to poly(A)-containing RNA from different preparations (isolated chioroplasts and total cell polyribosomes from the wild-type Z strain or from the aplastidic mutant W3BUL) were synthesized and used for hybridization experiments. a) In Euglena cells illuminated for 0, 1 or 24 h, 7- 10% of the total cell poly(A)-containing RNA are transcribed from chloroplast DNA. However, when RNA is extracted from isolated chloroplasts, this proportion of poly(A)-containing RNA is about two times higher (20%); in this case. the poly(A)-containing RNA could belong to a specific class and be transcribed from 18-20 % of the double-strand chloroplast DNA. b) In the dark-grown cultures or in the greening cultures, the major part of the total cell poly(A)-containing RNA is transcribed from the non-repetitive sequences of nuclear DNA. The isolated chloroplast preparations contain also a high proportion of poly(A)-containing RNA from nuclear origin. c) About 10% of the total cell poly(A)-containing RNA of the wild-type strain, absent in the poly(A)-containing RNA of the aplastidic mutant, appear hybridizable to the nuclear genome of this mutant. Thus the transcription of some of the RNA encoded by nuclear DNA could be controlled by the presence of the chloroplast. Moreover, the fact that isolated chioroplast preparations appear to be enriched in such poly(A)-containing RNA from nuclear origin, suggests that these RNA are located at the level of the chloroplast. [ABSTRACT FROM AUTHOR]

This paper reports the time course of development of the intramitochondrial cholesterol side-chain-cleavage activity, cytoplasmic NADP+-dependent isocitric dehydrogenase, malic enzyme and glucose-6-phosphate dehydrogenase during ovarian maturation, using as a model the immature rat ovary stimulated to develop with pharmacological doses of gonadotrophin. These enzymic activities were correlated with increases in ovarian content of DNA, cellular content of adenosine 3′:5′-monophosphate, and the levels of plasma progesterone. The plasma progesterone concentrations followed closely the development of the [4-14C]cholesterol side-chain-cleavage which was mimicked by the cytoplasmic isocitric dehydrogenase; both enzymes increased in activity 28 times during the 6 days of this study. There was no correlation between adenosine 3′:5′-monophosphate levels and cholesterol side-chain cleavage or progesterone plasma concentrations. [ABSTRACT FROM AUTHOR]

The present paper describes an investigation, at the transcription level, in a thermosensitive sporulation mutant of Bacillus subtilis (ts-4) grown at the permissive (30 °C) or restrictive (42 °C) temperature where sporulation capacity is respectively expressed or arrested. These studies were carried out by analysing the ribonucleic acid from vegetative and stationary phase cells (t3 cells) grown under both conditions, by hybridization-competition experiments. It was found that about 32% of t3 RNA species synthesized on the heavy (H) strand and about 19% of those synthesized on the light (L) strand have distinct sequences, depending on the growth conditions of the ts-4 cells: permissive or restrictive conditions. No such difference was observed in a normal zero-stage asporogenic mutant grown under the same conditions. These results suggest, therefore, that at the restrictive temperature the block in sporulation capacity of this mutant might, at least partially, reside in a deficiency at the transcription level. The significance of transcription from the L strand of B. subtilis DNA reported by others was also investigated. Based on our hybridization-competition studies on different sporogenic and asporogenic mutants it was suggested that the expression of some vegetative genes on the L strand during sporulation might have a regulatory function in the ‘switch-on’ of spore genes on the H stand. [ABSTRACT FROM AUTHOR]

The interspecific hybrid Arbacia lixula ... × Paracentrotus lividus ... which stops developing at the onset of gastrulation, was previously found to contain much more DNA of maternal origin (P. lividus) than DNA of paternal origin. In spite of this, the RNA synthesized by the blocked gastrula hybridizes better with DNA of paternal type than with DNA of maternal type. An explanation of thru observation was sought in the present paper by means of saturation and competition experiments. The higher affinity of RNA from the hybrid gastrula for paternal DNA could be due to the fact that RNA of paternal type is complementary to a longer portion of the corresponding DNA than RNA of maternal type. This explanation was not satisfactory since the number of genes of paternal type which are active in the hybrid is not very different from the number of genes of maternal type. In normal embryos of A. lixula and P. lividus, RNA from unfertilized eggs and from plutei was found to be less competitive against labeled RNA from gastrulae than gastrula RNA itself. Transcription of the genome is therefore partially stage-specific. This stage-specificity is maintained in the hybrid as far as transcription of the maternal genome is concerned, but is lost as far as transcription of the paternal genome is concerned. The hybrid gastrula was shown to synthesize more RNA molecules of A. lixula type than does the normal gastrula of this species, whereas RNA of P. lividus type is produced in equal amounts m normal and in hybrid embryos. These observations explain the hybridization properties of the RNA synthesized by the blocked gastrula. The results suggest that the genes of paternal type that are very active in the hybrid are those genes which m normal embryos are transcribed at all stages of development and probably also in the adult. This class of genes is much more active in a foreign cytoplasm than in the cytoplasm of its own species. On the other hand, the genes whose activity is restricted to the gastrula stage m normal embryos are not active in the hybrid. This class of genes does not seem to function in a foreign cytoplasm. [ABSTRACT FROM AUTHOR]

This article presents corrigendum of various articles, published in the "European Journal of Biochemistry." The paper by A. G. Kourmanova et al. contains errors on pages 2350, 2352 and 2353. On page 2352, in the section entitled "Assessment of the Quantitative Ratio of the Three Variants of mlp Genes in Mistletoe Genomic DNA and Their Transcripts in mRNA' the first sentence should read "Two Primers, Universal for All Obtained Variants of Mistletoe Lectin Gene Sequences Were Designed."

High mobility group (HMG) 1 protein is a highly abundant and an evolutionarily conserved chromosomal protein with two homologous DNA-binding domains (HMG boxes), A and B, attached by a short basic region to an acidic C-terminal tail. The protein has been implicated in a number of fundamental biological processes including DNA replication, transcription, recombination and repair. We demonstrate that HMG1 is able to enhance cohesive-end and blunt-end DNA ligation by T4 DNA ligase via its B domain. The C-terminal flanking sequence of the B domain (seven basic residues out of ≈ 18) and a number of conserved amino-acid residues within the HMG box (mainly basic or hydrophobic) are required for efficient stimulation of ligation. Pull-down assays, electron and scanning force microscopy revealed that HMG1 can associate two DNA molecules via their ends even in the absence of complementary overhangs. We propose that HMG1 protein may be involved in the rejoining of DNA breaks by different DNA ligases due to its ability to bring DNA duplexes and their termini into a close proximity while leaving the ends accessible for ligation. [ABSTRACT FROM AUTHOR]

In a previous paper, we reported on the structural properties of a 35-residue peptide corresponding to a modified basic subdomain (bSD) of the basic zipper protein c-Jun (residues 252–281) as determined by combined use of 1H-NMR, circular dichroism (CD) and Fourier transform infrared (FT-IR) spectroscopies [Krebs, D., Dahmani, B., El Antri, S., Monnot, M., Convert, O., Mauffret, O., Troalen, F. & Fermandjian, S. (1995) Eur. J. Biochem. 231, 370–380]. The fragments NP and CP (the N-terminal residues 1–19 and C-terminal residues 16–35 of bSD, respectively) proved to be particularly useful for the assignment of the 1H-NMR spectra of the full-length bSD, which has been achieved completely in aqueous solution and partially in trifluoroethanol. Here, we report on the structural properties of NP and CP in aqueous solution and under varying H2O/trifluoroethanol conditions, again using 1H-NMR, CD and FT-IR experiments. Both CD and FT-IR results established that the fragments are weakly structured in aqueous solution. Addition of trifluoroethanol to aqueous solutions of the peptides produced their stabilization into helix, following a profile sigmoidal for NP and nearly linear for CP. Quantitative NOEs, secondary · Hα chemical shifts, NH temperature coefficients and 3JαN coupling constants for the peptides in aqueous solutions provided indications for weak helix features (nascent helices) manifested within two sites (continuous dNN NOEs) in both NP and CP. For each peptide, an excellent agreement was observed between experiments and predictions with the AGADIR program for the location of these nascent helices in the sequences. Trifluoroethanol provoked both the α-helix stabilization within these sites and the α-helix propagation to adjacent amino acid residues. Finally, our results reflected the high flexibility and helix potential of the NP and CP fragments, these two properties seeming crucial for the accomodation of c-Jun to its specific DNA targets. The results demonstrated also the fragmentation's benefits in dissecting a protein or a complex peptide into smaller fragments and analyzing their structure individually. [ABSTRACT FROM AUTHOR]

Characterizes lectin cDNA clones encoding the two mannose-binding lectins from the bulbs of ramsons, Allium ursinum L. Sequence comparison of the different cDNA clones; Occurrence of glycosylated lectin precursors in the organelle fraction of radioactively labeled ramson bulbs; Difference in the organization of the lectin genes in A. ursinum and A. sativum.

The remodeling of nucleoproteins during dog-fish spermiogenesis involves two successive nuclear protein transitions: the first from somatic-type histones to transition proteins during the nuclear elongation of spermatids and the second leading to protamine-DNA association in mature spermatozoa. The chromatin of elongating spermatids contains two transition proteins called S1 and S2. The amino acid sequence of protein S1, a polypeptide of 87 residues was determined previously [Chauvière, M., Martinage, A., Briand, G., Sautière, P. & Chevaillier, Ph. (1987) Eur. J. Biochem. 169, 105-111]. In the present paper, we report the elucidation of the primary structure of the minor transition protein S2 established by automated Edman degradation of the protein and of its fragments generated by cleavage at methionine and aspartate residues. S2 contains 80 residues and has a molecular mass of 9726 Da. S2 is mainly characterized by a high content of basic amino acids mostly represented by lysine, a relatively high level of hydrophobic residues, the presence of six phosphorylatable residues and the lack of cysteine. Its amino acid sequence shows that the N-terminal half is highly basic, while the acidic residues are located in the C-terminal part of the protein where more diversity in amino acids is noticed. The two transition proteins S1 and S2 share striking structural similarities. Few but significative similarities have been detected with the mammalian transition protein TP1 [Kistler, W. S., Noyes, C., Hsu, R. & Heinrikson, R. L. (1975) J. Biol. Chem. 250, 1847-1853], suggesting similar functions for all these proteins in chromatin remodeling during sperm differentiation. By contrast, the two dog-fish spermatid-specific proteins are structurally unrelated to sperm protamines and cannot be considered as their precursors. [ABSTRACT FROM AUTHOR]

The inhibitory effects of hexasodium sym-bis(m-aminobenzoyl-m-amino-p-methylbenzoyl-1-naphthylamino-4,6,8-trisulfonate)carbamide (trivial name: suramin) on the activities of various deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) polymerases from mammalian cells, bacteria and retrovirus were examined and compared with each other. Among the various DNA and RNA polymerases tested, the activities of DNA primase, DNA polymerase α, reverse transcriptase and Escherichia coli RNA polymerase were strongly inhibited by suramin, while the activities of other enzymes including DNA polymerases β and γ, terminal deoxynucleotidyl-transferase and DNA polymerase I were relatively resistant to inhibition by this drug. The inhibition by suramin of DNA polymerase α from KB cells and Rauscher murine leukemia virus (RLV) reverse transcriptase was due to competition with the respective template, primer (activated DNA for α polymerase and (rA)n · (dT)12-18 for reverse transcriptase) for the template · primer-binding site of the enzyme, while the inhibition of DNA primase and E. coli RNA polymerase was due to competition with the ribonucleoside triphosphate substrate. The inhibition constants (Ki) of suramin were determined to be 2.6 µM, 0.35 µM, 0.54 µM and 0.70 µM for DNA primase, DNA polymerase α, RLV reverse transcriptase and E. coli RNA polymerase respectively. The observed inhibitions of these polynucleotide-synthesizing enzymes by suramin seem to explain, at least in part, an as yet unknown mechanism of trypanocidal action of this drug. [ABSTRACT FROM AUTHOR]

Human DNA was fractionated by centrifugation in Cs2SO4 density gradients containing 3,6-bis(acetatomercurimethyl)dioxane (BAMD). Fractions were investigated in their analytical CsCI profiles and d number of specific sequences were localized in them. The results so obtained led to an improved understanding of the organization of nucleotide sequences in the human genome, as well as to the discovery that a class of DNA having a very high G + C content and not represented in the mouse genome, is particularly rich in genes and interspersed repetitive sequences. [ABSTRACT FROM AUTHOR]

In Bacillus subtilis, 5-azacytidine, an analog of cytidine, causes a time- and dose-dependent growth inhibition. Methyl donors are unable to overcome azacytidine-induced inhibition while pyrimidine nucleosides, except orotidine, can revert this inhibition totally. On the other hand, pyrimidine bases, except uracil, are unable to restore growth in azacytidine-treated cells. Uracil, at a high concentration, can revert growth inhibition only inefficiently. However, a considerable relief of growth inhibition by uracil occurs in the presence of a ribose donor. In azacytidine-treated B. subtilis cells methylation of bases in DNA is not affected either quantitatively or qualitatively and DNA methyltransferase activity remains unaltered as compared to the untreated cells, apparently due to the absence of azacytidine incorporation into the DNA. The inability of B. subtilis cytidine kinase to phosphorylate azacytidine is the probable reason for this non-incorporation. Analysis of the enzymes of de novo pyrimidine biosynthesis has shown that orotidine monophosphate pyrophosphorylase is specifically repressed by azacytidine treatment. [ABSTRACT FROM AUTHOR]

The nucleotide sequence of a 3180-base-pair segment of DNA, containing the sucA gene encoding the 2-oxoglutarate dehydrogenase component (Elo) of the 2-oxoglutarate dehydrogenase complex of Escherichia coli, has been determined by the dideoxy chain-termination method. The sucA structural gene contains 2796 base pairs 1932 codons, excluding the initiation codon AUG) and encodes a polypeptide having a glutamine residue at the amino terminus, a glutamate residue at the carboxy-terminus and a calculated Mr = 104905. The predicted amino acid composition is in good agreement with published information obtained by hydrolysis of the purified enzyme. There is a striking lack of sequence homology between the 2-oxoglutarate dehydrogenase (E1o) and the corresponding pyruvate dehydrogenase (E1p) which suggests that the two components are not closely related in evolutionary terms. The location and polarity of the sucA gene, relative to the restriction map of the corresponding segment of DNA, are consistent with it being the proximal gene of the suc operon, as defined in previous genetic and post-infection labelling studies, but it could also form part of a more complex regulatory unit. The sucA gene is preceded by a segment of DNA thai contains many substantial regions of hyphenated dyad symmetry including an IS-like sequence of the type that is thought to function as an intercistronic regulatory element. This segment also contains three putative RNA polymerase binding sites and a good ribosome binding site. [ABSTRACT FROM AUTHOR]

The problem of the coordination between cyclic events in the DNA assembly line and the cell envelope assembly tine was approached with the technique of synchronized cultures. Escherichia co/i strains ML 30, K12 3300, K12 PC2, K12 BB2014 and B/rF were synchronized by repeated cycles of mass doubling followed by short phosphate starvation periods. Steady-state balanced growth was obtained by subsequent incubation in non-limiting growth conditions for one or more generation times. Several successive cell cycles were monitored for mass increase and cell number, while the rate of DNA synthesis and the rate of phospholipid synthesis were usually measured with more than one method. In all strains, and in strain ML 30 in five different growth media giving doubling times from 20-110 mm, a discontinuity in the rate of synthesis of phosphatidylethanolamine and of phosphatidylglycerol was observed. These two major phospholipid components of inner and outer membranes were synthesized at a constant rate per cell for a large portion of the cell cycle and the rate of synthesis of both increased twofold at the same time. This cyclic program was reproducible not only in successive cell cycles, but also in separate experiments with the same strain, in the same medium. In contrast, differences in timing were observed with different strains, and in the same strain with different carbon sources. In particular, the simultaneity of the increase in phospholipid synthesis either with DNA initiation or with cell division could not be observed as a rule. [ABSTRACT FROM AUTHOR]

Chromatin proteins from rat liver contain a repair activity that removes O6-ethylguanine from ethylnitrosourea-treated DNA. This activity does not depend on divalent cations and works in the presence of EDTA, but does depend on the presence of free thiol groups. Thus, it is destroyed by N-ethylmaleimide and is protected by half-life at 35°C is 55 min, but DNA, ethylated or not, affords some protection. The repair reaction is a transethylation from O6-ethylguanine in DNA onto two different cysteine residues contained in acceptor proteins. The reaction can be followed by monitoring the appearance of ethylated proteins or by disappearance of O6-ethylguanine from DNA. [ABSTRACT FROM AUTHOR]

Cell nuclei prepared from liver were alkylated in vitro with ethylnitrosourea; the nuclear DNA was found to lose O6-ethylguanine and 7-ethylguanine during a subsequent incubation at 37°C. The rate of O6-ethylguanine loss is comparable to that observed in vivo, indicating that no cytoplasmic component is needed for the repair; no free O6-ethylguanine was found in the incubation medium of the ethylated nuclei. The rate of 7-ethylguanine loss is higher than the spontaneous depurination in vitro and an amount of free-7-ethylguanine equivalent to that loss by the nuclear DNA was found in the incubation medium; these results suggest that this DNA lesion is excised by DNA glycosylase. The protein of the chromatin prepared from the isolated nuclei induced the disappearance of O6-ethylguanine from an added ethylated DNA. No free O6-ethylguanine was released indicating that the repair is not catalyzed by a DNA glycosylase; no oligonucleotides enriched in O6-ethylguanine from DNA is not the result of the cooperative action of a specific endonuclease and an exonuclease. Activities capable of removing O6-ethylguanine from DNA were found in other cell compartments; most of it, however, is in the nucleus where the main location is chromatin. A pretreatment of the rats with daily low doses of diethylnitrosamine during 3 or 4 weeks increased 2–3 times the repair activity of the chromatin proteins. [ABSTRACT FROM AUTHOR]

The increase in cytochrome c oxidase activity in pea cotyledons during seed hydration was investigated with two kinds of antibodies against the enzymes purified from mitochondria of pea shoot and sweet potato root. The antibody against the pea enzyme recognized only the largest of the enzyme subunits (subunit I), while that against the sweet potato one did other three of the pea enzyme subunits: the second largest (subunit II) and the two smallest (subunits IV and V). 1. There was no increase in the amount of protein immunoprecipitated with the anti-(pea enzyme) antibody in a crude fraction of cotyledon membranes during seed hydration, despite the marked increase in cytochrome c oxidase activity. Neither cycloheximide nor chloramphenicol had any effect on the activity or the amount. The crude membrane fraction from dry cotyledons contained an enzymatically inert protein precipitated with the anti-(pea enzyme) antibody. The inert protein could be separated from the active enzyme protein through solubilization of the protein from the membranes with various concentrations of Triton X-100. It consisted of only one kind of polypeptide with the same molecular weight as subunit I and decreased with the concomitant increase in the active enzyme protein during seed hydration. 2. Dry pea cotyledons also contained a soluble protein that was immunoprecipitated by antibody to the sweet potato enzyme. The soluble form of the immunoreactive protein decreased with the concomitant increase in active cytochrome c oxidase protein in the crude membrane fraction from the cotyledons during seed hydration. None of these changes during seed hydration were inhibited by cycloheximide or chloramphenicol. The soluble, immunoreactive protein contained only one kind of polypeptide, of which the molecular weight was identical to that of subunit IV. 3. The mitochondrial inner membranes of dry cotyledons were separated into three fractions by sucrose density gradient centrifugation. The lightest was the richest of the three in the enzymatically inert protein immunoprecipitated with the anti-(pea enzyme)antibody; cytochrome c oxidase activity in this fraction increased immediately after the onset of seed hydration. These results indicate that a membrane-bound, free form of subunit I and a soluble, free form of subunit IV of cytochrome c oxidase exist in dry pea cotyledons. We proposed that these free forms of subunits are assembled with the other subunits to form the active cytochrome c oxidase during seed hydration. [ABSTRACT FROM AUTHOR]

The specific activities of rat liver and kidney DNA pyrimidines increase in animals which have had [2-14C]-orotic acid administered several days before killing. This phenomenon is caused by the reutilization of the performed labeled pyrimidine components originating mainly from degraded RNAs of the organism. [ABSTRACT FROM AUTHOR]

Ellipticine is the type of a group of substances used against human cancer. It was shown that ellipticine and 9-methoxyellipticine strongly interact with monolayers of negatively charged phospholipids. In the present paper it is shown by spectrophotometric methods that ellipticine interacts with suspensions of a model membrane with a 1/1 charge neutralization, and with a natural membrane, both negatively charged. At a physiological pH, ellipticine undergoes protonation in the presence of these membranes. Its apparent pK is increased by 1, and its spectral behaviour, when the pH is changed, indicates that the drug is in a less polar environment, suggesting that hydrophobic bonds link the drug and the lipids. The existence of such bonds is suggested by the fact that the drug is not significantly released from anionic membranes when the pH is increased to 10, at which value ellipticine is not ionized. The consequences of these ionic and hydrophobic interactions are briefly discussed. [ABSTRACT FROM AUTHOR]

Considering enzymatic activities found in bacteria and in animal cells, there are two possible mechanisms for repair of N-methylated purines produced by methylating agents such as the mutagen and carcinogen N-methyl-N′-nitro-N-nitrosoguanidine. Both mechanisms involve first an enzymatic removal of the methylated bases by glycosylases. The resulting apurinic sites could then be repaired by (a) direct insertion of the correct bases purine insertases or (b) opening of the polynucleotide chain by apurinic endonuclease followed by repair synthesis. As the methods commonly used to detect lesions induced by methylating agents involve alkali, it was thus far not possible to decide between the above possibilities because apurinic sites are by themselves alkali labile. In this paper I describe two methods which avoid alkali and therefore allow the clarification of some aspects of the repair reaction. One of these methods makes use of 95% formamide at 40 °C in place of alkali to denature DNA with pre-existing single-strand breaks, the other measures the capacity of DNA scissions with free 3′-OH groups to act as primer for Escherichia coli DNA polymerase I. Results obtained with both methods make it unlikely that purine insertases play a major role in the repair of apurinic sites. Kinetics of production and repair of single-strand breaks, produced in 3T6 mouse fibroblasts by incubation with N-methyl-N′-nitro-N-nitrosoguanidine, were also examined using the methods of alkaline elution and alkaline sucrose gradient centrifugation. [ABSTRACT FROM AUTHOR]

Investigates the reassociation kinetics of DNA fragments obtained from the major components of the mouse and human genomes. Presence of variations in in the sequence organization of mammalian genomes; Components of DNA. [ABSTRACT FROM AUTHOR]

DNA methyltransferase was purified 310-fold from a green alga, Chlamydomonas reinhardi vegetative cells. The native enzyme of molecular weight 55 000–58 000 catalyzed the transfer of methyl groups from S-adenosylmethionine to the 5 position of cytosine in DNA. Native DNA accepted methyl groups 10-fold more than did denatured DNA. The sequence specificity analysis of methylated deoxycytidine in vitro revealed that the enzyme introduces methyl groups preferentially into sequences containing 5′d(T-mC-R)3′. Kinetic analysis of the reaction indicated that the enzyme obeys a random sequential mechanism. The extent of saturation with methyl groups depends upon the species from which the DNA was obtained. Kinetic analysis of the reaction catalyzed by RNA polymerase II has indicated that DNA methylation decreases the rate of initiation of RNA synthesis, but does not affect the rate of RNA chain elongation. [ABSTRACT FROM AUTHOR]

Fragment Hind-B-C2, the second largest DNA restriction fragment generated by digestion of fragment Hind-B with the endo R · EcoRII enzyme, represents 4.4% of the Simian virus 40 (SV40) genome. The complete nucleotide sequence (231 base pairs) of this fragment has been determined by application of the procedure of Maxam and Gilbert (1977). This region is believed to code for the carboxyl-terminal part of the T antigen. On the basis of the termination code words in the strand with the same polarity as the early mRNA, two open reading frames for translation could be defined. Only one of these, however, extends through the adjacent Hind-B-C1 fragment and is therefore believed to dictate the primary structure of the T antigen. It terminates within Hind-B with a TAA signal. The region, determined by the second open frame, is large enough to code for a protein of Mr about 11 000. The regions in SV40 DNA from which the non-translated regions of the early and late mRNAs are transcribed overlap over nearly their entire length. Although this spacer region is very (dA+dT)- rich, a secondary structure model can be proposed which is centered around map position 0.17. The RNA copy of the untranslated region also contains the sequence A-A-U-A-A-A, common to all other eukaryotic mRNA molecules sequenced so far: it is present once on the late mRNA and twice on the early messenger RNA. Also a sequence of 6 or 7 successive thymidine residues is present in the early and late DNA strand respectively, 131 and 95 nucleotides beyond the polypeptide termination codons, and these may perhaps play a role in termination of transcription. Of particular interest may be the carboxyl terminus of the T antigen; the terminal tryptic peptide is 10 residues long, six of which are proline. [ABSTRACT FROM AUTHOR]

A DNA-stimulated ATP-γ-phosphohydrolase of molecular weight 75 000 was purified from Escherichia coli cells. The ATPase, a globular molecule (identical probably with an ATPase described previously by Richet and Kohiyama in 1976) shows specificity for adenine nucleotides, it prefers single-stranded DNA as the cofactor, it exhibits a complicated mode of response to variations of the cofactor concentration and it is devoid of nuclease activity. Preparations derived from rep3 mutant cells yield widely varying amounts of an apparently normal ATPase. [ABSTRACT FROM AUTHOR]