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The structural organization of the entire human nuclear encoded gene for mitochondrial cytochrome c1 was determined by analyzing a clone obtained from an EMBL3 genomic DNA library. The gene spans 2.4-kilobase pairs and contains seven exons interrupted by six introns of relatively small sizes. All intron/exon splice junctions follow the GT/AG rule. The 5'-flanking region of the gene lacks typical transcriptional regulatory sequence elements such as TATA and CAAT boxes but contains seven putative GC boxes (Sp1 binding sites) and several sequences that resemble another type of the Sp1 responsive element, the enhancer core consensus sequence, the AP-1 responsive element, and the cAMP- and phorbol ester-inducible element. The region also contains a 15-nucleotide sequence highly homologous to the AP-4 consensus sequence and to those in the 5'-flanking regions of the genes for two enzymes associated with respiratory function, the beta subunit of human ATP synthase and chicken 5-aminolevulinate synthase. The presequence, which is essential for the transport of the cytochrome c1 precursor into mitochondria, is encoded in both the first and second exons, and the nucleotide sequence corresponding to the presequence is separated by the first intron. This is the first example of a leader sequence coding for a presequence clearly separated into two parts by an intron.

Summary ALG-2 belongs to the penta-EF-hand (PEF) protein family and interacts with various intracellular proteins, such as Alix and TSG101, that are involved in endosomal sorting and HIV budding. Through X-ray crystallography, we solved the structures of Ca 2+ -free and -bound forms of N-terminally truncated human ALG-2 (des3-20ALG-2), Zn 2+ -bound form of full-length ALG-2, and the structure of the complex between des3-23ALG-2 and the peptide corresponding to Alix799-814 in Zn 2+ -bound form. Binding of Ca 2+ to EF3 enables the side chain of Arg125, present in the loop connecting EF3 and EF4, to move enough to make a primary hydrophobic pocket accessible to the critical PPYP motif, which partially overlaps with the GPP motif for the binding of Cep55 (centrosome protein 55 kDa). Based on these results, together with the results of in vitro binding assay with mutant ALG-2 and Alix proteins, we propose a Ca 2+ /EF3-driven arginine switch mechanism for ALG-2 binding to Alix.

l,l-Diaminopimelate aminotransferase (DapL) is an enzyme required for the biosynthesis of meso-diaminopimelate (m-DAP) and l-lysine (Lys) in some bacteria and photosynthetic organisms. m-DAP and Lys are both involved in the synthesis of peptidoglycan (PG) and protein synthesis. DapL is found in specific eubacterial and archaeal lineages, in particular in several groups of pathogenic bacteria such as Leptospira interrogans (LiDapL), the soil/water bacterium Verrucomicrobium spinosum (VsDapL) and the alga Chlamydomonas reinhardtii (CrDapL). Here we present the first comprehensive inhibition study comparing the kinetic activity of DapL orthologs using previously active small molecule inhibitors formerly identified in a screen with the DapL of Arabidopsis thaliana (AtDapL), a flowering plant. Each inhibitor is derived from one of four classes with different central structural moieties: a hydrazide, a rhodanine, a barbiturate, or a thiobarbituate functionality. The results show that all five compounds tested were effective at inhibiting the DapL orthologs. LiDapL and AtDapL showed similar patterns of inhibition across the inhibitor series, whereas the VsDapL and CrDapL inhibition patterns were different from that of LiDapL and AtDapL. CrDapL was found to be insensitive to the hydrazide (IC50 >200μM). VsDapL was found to be the most sensitive to the barbiturate and thiobarbiturate containing inhibitors (IC50 ∼5μM). Taken together, the data shows that the homologs have differing sensitivities to the inhibitors with IC50 values ranging from 4.7 to 250μM. In an attempt to understand the basis for these differences the four enzymes were modeled based on the known structure of AtDapL. Overall, it was found that the enzyme active sites were conserved, although the second shell of residues close to the active site were not. We conclude from this that the altered binding patterns seen in the inhibition studies may be a consequence of the inhibitors forming additional interactions with residues proximal to the active site, or that the inhibitors may not act by binding to the active site. Compounds that are specific for DapL could be potential biocides (antibiotic, herbicide or algaecide) that are nontoxic to animals since animals do not contain the enzymes necessary for PG or Lys synthesis. This study provides important information to expand our current understanding of the structure/activity relationship of DapL and putative inhibitors that are potentially useful for the design and or discovery of novel biocides.

In autophagy, which is an intracellular degradation system that is conserved among eukaryotes, degradation targets are sequestered through the de novo synthesis of a double-membrane organelle, the autophagosome, which delivers them to the lysosomes for degradation. The core autophagy machinery comprising 18 autophagy-related (Atg) proteins in yeast plays an essential role in autophagosome formation; however, the molecular role of each Atg factor and the mechanism of autophagosome formation remain elusive. Recent years have seen remarkable progress in structural biological studies on the core autophagy machinery, opening new avenues for autophagy research. This review summarizes recent advances in structural biological and mechanistic studies on the core autophagy machinery and discusses the molecular mechanisms of autophagosome formation.

The oral administration of stannous chloride (Sn 2+ , 3 mg/100 g body weight) to rats, twice a day for 3 days, markedly increased serum glucose concentration and significantly reduced serum insulin levels following a single oral administration of glucose (0.2 g/100 g), compared with results on control rats. The results indicate that tin administration prevents the secretion of insulin stimulated by glucose.

Chlorination, bromination and iodination of bis(methylthio)tetrathiafulvalene (BMT-TTF) produced mainly the dihalogenated products (BMT-TTFX2) with small amounts of the monohalogenated derivatives (BMT-TTFX). The molecular structures of BMT-TTFBr2 and BMT-TTFBr2•I3 have been determined, and the conductivities of CT-complexes and radical salts derived from BMT-TTFX2 have been measured.