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Arabidopsis thaliana BOR1 was the first boron (B) transporter identified in living systems. There are four AtBOR1-like genes, OsBOR1, 2, 3 and 4, present in the rice genome. We characterized the activity, expression and physiological function of OsBOR4. OsBOR4 is an active efflux transporter of B. Quantitative PCR analysis and OsBOR4 promoter–green fluorescent protein (GFP) fusion revealed that OsBOR4 was both highly and specifically expressed in pollen. We obtained five Tos17 insertion mutants of osbor4. The pollen grains were viable and development of floral organs was normal in the homozygous osbor4 mutants. We observed that in all Tos17 insertion lines tested, the frequency of osbor4 homozygous plants was lower than expected in the progeny of self-fertilized heterozygous plants. These results establish that OsBOR4 is essential for normal reproductive processes. Pollen from osbor4 homozygous plants elongated fewer tubes on wild-type stigmas, and tube elongation of mutant pollen was less efficient compared with the wild-type pollen, suggesting reduced competence of osbor4 mutant pollen. The reduced competence of mutant pollen was further supported by the crosses of independent Tos17-inserted alleles of OsBOR4. Our results suggest that OsBOR4, a boron efflux transporter, is required for normal pollen germination and/or tube elongation. [ABSTRACT FROM PUBLISHER]

The dasD gene is located just downstream of the dasABC gene cluster, encoding components of an ABC transporter for uptake of a chitin-degradation product N,N′-diacetylchitobiose [(GlcNAc)2] in Streptomyces coelicolor A3(2). To clarify the roles of the DasD protein in the degradation and assimilation of chitin, we obtained and characterized a recombinant Das D protein and a dasD-null mutant of S. coelicolor A3(2). The recombinant Das D protein produced in Escherichia coli showed N-acetyl-β- d-glucosaminidase ( Glc NAcase) activity and its optimum temperature and pH were 40 °C and 7, respectively. dasD transcription was strongly induced in the presence of chitin, weakly by chitosan, but not by cellulose or xylan in S. coelicolor A3(2). Immuno-blot analysis demonstrated that Das D is a cytoplasmic protein. The dasD-null mutant exhibited cellular Glc NAcase activity which was comparable with that of the parent strain M145. Das D, thus, did not seem to be a major Glc NAcase. Induced extracellular chitinase activity in the dasD-null mutant was, interestingly, higher than M145, in the presence of colloidal chitin or ( Glc NAc)2. In contrast to M145, ( Glc NAc)2 temporally accumulated in the culture supernatant of the dasD-null mutant in the presence of colloidal chitin. [ABSTRACT FROM AUTHOR]

The article presents the findings of a research conducted on examining the determination of hydrolytic specificities of enzyme chitosanases. It discusses the methodology used in conducting the research including high performance liquid chromatography (HPLC), thin-layer chromatography and mass spectrometry. It concludes that the findings of the research classify chitosanases into four distinct subclasses.

The article focuses on a study which aims to determine physiological interaction between Aleuria aurantia lectin (AAL) produced in the mycelia and fruit-bodies of the ascomycete fungus Aleuria aurantia that hampers zygomycete fungus Mucor racemosus growth. It reports that AAL specifically bound to the hyphae of M. racemosus that inhibits its growth. The minimal concentration of AAL required to inhibit and disrupt the growth of fungus is also included.

Although Streptomyces species are major chitin-degraders in soil ecosystems, the expression of the diverse chitinase genes within Streptomyces coelicolor grown in soil has not been assessed. As a first step, the induction pattern of nine chitinase genes in S. coelicolor growing in autoclaved soil was compared with those in liquid cultures. The relative expression levels of nine chitinase genes were measured using real-time reverse transcription PCR. The expression of all chitinase genes was induced by chitin in both autoclaved soil and liquid cultures, but to different levels. The expression levels of five chitinase genes in autoclaved soil were significantly higher than those in the liquid cultures. In particular, a putative chitinase gene, chitinase H, showed the highest induction in autoclaved soil. The same induction pattern was confirmed in nonautoclaved soil, indicating that soil contains some factors affecting the expression of chitinase genes. The chiH gene product, ChiH, cloned in Streptomycetes lividans was secreted and exhibited chitin degradation activity that was stable within a wide range of acidic pHs. The disruption of dasR, a transcriptional regulator for the uptake of N-acetylglucosamine, abolished the expression of chiH, demonstrating that DasR is required for the regulation of ChiH expression. [ABSTRACT FROM AUTHOR]

Because of the high demand for iron of the photosynthetic apparatus in thylakoid membranes, iron deficiency primarily affects the electron transfer between the two photosystems (PSI and PSII), resulting in photooxidative damage in plants. However, in barley, PSII is protected against photoinhibition, and the plant survives even with a low iron content in its chlorotic leaves. In this study, we report an adaptation mechanism of the photosynthetic apparatus in barley to iron deficiency, which is concomitant with the remodeling of a PSII antenna system. Transcriptome analysis revealed that long-term iron deficiency induced the expression of two genes of the major light-harvesting Chl a/b-binding protein of PSII (LHCII), namely HvLhcb1.11 and HvLhcb1.12. Chl fluorescence analysis of the wild type and Lhcb1-less chlorina mutants clearly showed that non-photochemical quenching (NPQ) of the wild type was increased by approximately 200% by iron deficiency, whereas NPQ of chlorina mutants did not change significantly under iron deficiency. The mutant showed severe photodamage in young leaves under prolonged iron deficiency, suggesting that the HvLhcb1 protein is essential for both thermal dissipation and photoprotection in iron-deficient barley. Analysis of thylakoid protein complexes revealed that the proportion of the monomeric form of Lhcb1 significantly increased in barley grown under iron-deficient conditions. We hypothesize that alteration of the HvLhcb1 subpopulations modifies the organization of LHCII in the thylakoid membranes, which is a key step for thermal dissipation to compensate for excess excitation energy and thereby protect the photosystems from serious damage in iron-deficient barley leaves. [ABSTRACT FROM AUTHOR]

The article presents a study on the overproduction and purification of oligoxylosyl transfer enzyme (OxtA)[(H)E], a N-terminally His-tagged recombinant form of OxtA, in Escherichia coli. It notes that the purified OxtA(H)E showed a high transxylosylation activity. Moreover, the deduced amino acid sequence of OxtA(H)E revealed a complete resemblance to xylanases, which belongs to a family 11 of glycosyl hydrolase.

An actinomycete strain, Amycolatopsis sp. CsO-2, produces a 27-kDa chitosanase. To reveal the molecular characteristics of the enzyme, its corresponding gene ctoA was cloned by a reverse genetic technique, based on the N-terminal amino acid sequence of the protein. The encoded CtoA protein was deduced to be composed of 286 amino acids, including a putative signal peptide (1–48), and exhibited 83% identity in the amino acid sequence with the family 46 chitosanases from Streptomyces sp. N174 or Nocardioides sp. N106. The active recombinant CtoA protein was successfully overproduced in Escherichia coli. The mutant protein E22Q, in which the glutamic acid residue 22 was replaced with glutamine, abolished the chitosanase activity, showing that the Glu22 residue is required for the enzymatic activity. CtoA exhibited antifungal activity against Rhizopus oryzae, which is known to produce chitosan probably as a cell wall component. In contrast, E22Q did not inhibit the growth of the fungus, suggesting that chitosan-hydrolyzing activity is essential for the antifungal activity. It is noteworthy that the antifungal effect of CtoA against R. oryzae was drastically enhanced by the simultaneous addition of the family 19 chitinase ChiC from Streptomyces griseus. [ABSTRACT FROM AUTHOR]

The article focuses on pseudomonas isolated with chitosan-degrading activity. The chitosanase (Cto1) was purified and it was determined that its N-terminal amino acid sequence and the gene (Cto1) were cloned by a reverse-genetic technique wherein the encoded protein shows a sequence similar to known family-46 chitosanases. Cto1 was overproduced and was secreted by a Brevibacillus choshinensis.

The article discusses the results of a study which compared the enzymatic and antifungal properties of family 19 and family 18 chitinases from Streptomyces coelicolor. The hydrolytic activity of Chi19F from family 19, against soluble substrates was higher as compared with three family 18 chitinases. Chi18aC from family 19 has the highest activity against crystalline substrates.

The article focuses on the determination of the specificity of the sugar-binding protein NgcE, a component of the ABC Transporter for N-Acetylglucosamine in Streptomyces olivaceoviridis, in an enzyme-linked immunosorbent assay. The ATP-binding cassette transporter Ngc for N-acetylglucosamine of streptomyces olivaceoviridis compromises the solute-binding protein NgcE, which was used to develop a generally applicable enzyme-linked immunosorbent assay system.

The article focuses on the characterization of a lectin from mushroom Grifola frondosa (GFL). The amino acid sequence suggests that GFL is the first example of a jacalin-related lectin of fungal origin. REsults suggests that hemagglutinating activity in three stages of fruiting body formation involves the fruiting body, primordium, and mycelial mat.

Determines the amino-terminal amino acid sequence of the purified protein that lead to cloning of a gene encoding the chitinase promoter-binding protein. Role of Streptomyces as a major decomposer of the chitin in soil; Preparation of plasmid DNA from Escherichia coli cells; Measurement of chitinase activity.