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991.
Legumains - a family of asparagine-specific cysteine endopeptidases involved in propolypeptide processing and protein breakdown in plants 总被引:3,自引:0,他引:3
Legumains are a recently discovered family of plant and animal cysteine endopeptidases with a cleavage specificity for Asn in the P1 position of peptide bonds. Asp-flanked peptide bonds also are cleaved, but with a much lower efficiency. Legumains evolved from GPI transamidase-like progenitors. Sequence analysis revealed three major groups of plant legumains corresponding to differences in the developmental and organ-specific gene expression. With the exception of a single cell wall specific representative, all legumains occur in the vacuolar compartment. Legumains are either involved in protein degradation or play a role in the processing of precursor proteins by Asn/Asp-specific limited proteolysis. Which function legumains perform depends on the conformational state of the substrate protein. A legumain acts as a vacuolar processing enzyme when it only has access to the regular processing sites of a precursor polypeptide, but it acts as a degradative enzyme when an altered conformation opens the substrate for unlimited proteolysis. The specificity of these interactions seems to be the result of a co-evolution of enzyme and substrate. The double function of legumains is particularly evident in the events of deposition and mobilisation of storage globulins during seed maturation and germination/seedling growth and in senescing and dying cells. 相似文献
992.
Hong Zhang Tianjun Zhou Oleg Kurnasov Sara Cheek Nick V Grishin Andrei Osterman 《Structure (London, England : 1993)》2002,10(1):69-79
Nicotinamide/Nicotinate mononucleotide (NMN/NaMN) adenylyltransferase is an indispensable enzyme in both de novo biosynthesis and salvage of NAD+ and NADP+. In prokaryotes, it is absolutely required for cell survival, thus representing an attractive target for the development of new broad-spectrum antibacteria inhibitors. The crystal structures of E. coli NaMN adenylyltransferase (NMNAT) and its complex with deamido-NAD (NaAD) revealed that ligand binding causes large conformational changes in several loop regions around the active site. The enzyme specifically recognizes the deamidated pyridine nucleotide through interactions between nicotinate carboxylate with several protein main chain amides and a positive helix dipole. Comparison of E. coli NMNAT with those from archaeal organisms revealed extensive differences in the active site architecture, enzyme-ligand interaction mode, and bound dinucleotide conformations. The bacterial NaMN adenylyltransferase structures described here provide a foundation for structure-based design of specific inhibitors that may have therapeutic potential. 相似文献
993.
Ju He Mohsin Vora Rachel M. Haney Grigory S. Filonov Catherine A. Musselman Christopher G. Burd Andrei G. Kutateladze Vladislav V. Verkhusha Robert V. Stahelin Tatiana G. Kutateladze 《Proteins》2009,76(4):852-860
The FYVE domain associates with phosphatidylinositol 3‐phosphate [PtdIns(3)P] in membranes of early endosomes and penetrates bilayers. Here, we detail principles of membrane anchoring and show that the FYVE domain insertion into PtdIns(3)P‐enriched membranes and membrane‐mimetics is substantially increased in acidic conditions. The EEA1 FYVE domain binds to POPC/POPE/PtdIns(3)P vesicles with a Kd of 49 nM at pH 6.0, however associates ~24 fold weaker at pH 8.0. The decrease in the affinity is primarily due to much faster dissociation of the protein from the bilayers in basic media. Lowering the pH enhances the interaction of the Hrs, RUFY1, Vps27p and WDFY1 FYVE domains with PtdIns(3)P‐containing membranes in vitro and in vivo, indicating that pH‐dependency is a general function of the FYVE finger family. The PtdIns(3)P binding and membrane insertion of the FYVE domain is modulated by the two adjacent His residues of the R(R/K)HHCRXCG signature motif. Mutation of either His residue abolishes the pH‐sensitivity. Both protonation of the His residues and nonspecific electrostatic contacts stabilize the FYVE domain in the lipid‐bound form, promoting its penetration and increasing the membrane residence time. Proteins 2009. © 2009 Wiley‐Liss, Inc. 相似文献
994.
995.
Andrei V. Perepelov Dan Li Bin Liu Sof''ya N. Senchenkova Dan Guo Sergei D. Shevelev Alexander S. Shashkov Xi Guo Lu Feng Yuriy A. Knirel & Lei Wang 《FEMS immunology and medical microbiology》2009,57(1):80-87
The influence of antibiotic exposure in the early postnatal period on the development of intestinal microbiota was monitored in 26 infants including five antibiotic-treated (AT) subjects orally administered a broad-spectrum antibiotic for the first 4 days of life and three caesarean-delivered (CD) subjects whose mothers were intravenously injected by the similar type of antibiotics in the same period. The faecal bacterial composition was analysed daily for the first 5 days and monthly for the first 2 months. Terminal restriction fragment length polymor-phisms in the AT subjects showed less diversity with the attenuation of the colonization of some bacterial groups, especially in Bifidobacterium and unusual colonization of Enterococcus in the first week than the control antibiotic-free infants (AF, n =18). Quantitative real-time PCR showed overgrowth of enterococci (day 3, P =0.01; day 5, P =0.003; month 1, P =0.01) and arrested growth of Bifidobacterium (day 3, P =0.03) in the AT group. Furthermore, after 1 month, the Enterobacteriaceae population was markedly higher in the AT group than in the AF group (month 1, P =0.02; month 2, P =0.02). CD infants sustained similar, although relatively weaker, alteration in the developing microbiota. These results indicate that antibiotic exposure at the beginning of life greatly influences the development of neonatal intestinal microbiota. 相似文献
996.
The rhizobacterium Azospirillum brasilense Sp245 swims, swarms (Swa+ phenotype) or, very rarely, migrates with the formation of granular macrocolonies (Gri+ phenotype). Our aims were (i) to identify Sp245 mutants that swarm faster than the parent strain or differ from it in the mode of spreading and (ii) to compare the mutants’ responses to wheat seedling exudates. In isotropic liquid media, the swimming speeds of all motile A. brasilense strains were not influenced by the exudates. However, the exudates significantly stimulated the swarming of Sp245. In several Sp245 mutants, the superswarming phenotype was insensitive to local colonial density and to the presence of wheat seedling exudates. An A. brasilense polar-flagellum-defective Gri+ mutant BK759.G gave rise to stable Swa++ derivatives with restored flagellum production. This transition was concurrent with plasmid rearrangements and was stimulated in the presence of wheat seedling exudates. The swarming rate of the Swa++ derivatives of BK759.G was affected by the local density of their colonies but not by the presence of the exudates. 相似文献
997.
Christopher McGuigan Marco Derudas Maurizio Quintiliani Graciela Andrei Robert Snoeck Geoffrey Henson Jan Balzarini 《Bioorganic & medicinal chemistry letters》2009,19(22):6264-6267
We report the preparation of 2′-α-F, 2′-β-F and 2′,2′-difluoro analogues of the leading anti-varicella zoster virus (VZV) pentylphenyl BCNA Cf 1743. VZV thymidine kinase showed the highest phosphorylating capacity for the β-fluoro derivative, that retained equal antiviral potency as the parent compound. In contrast, the α-fluoro- and 2′,2′-difluoro BCNA derivatives were markedly less (100-fold) antivirally active. 相似文献
998.
Anh P. Truong Danielle L. Aubele Gary D. Probst Martin L. Neitzel Chris M. Semko Simeon Bowers Darren Dressen Roy K. Hom Andrei W. Konradi Hing L. Sham Albert W. Garofalo Pamela S. Keim Jing Wu Michael S. Dappen Karina Wong Erich Goldbach Kevin P. Quinn John-Michael Sauer Elizabeth F. Brigham William Wallace Guriqbal Basi 《Bioorganic & medicinal chemistry letters》2009,19(17):4920-4923
In this Letter, we report our strategy to design potent and metabolically stable γ-secretase inhibitors that are efficacious in reducing the cortical Aβx-40 levels in FVB mice via a single PO dose. 相似文献
999.
1000.
Massively parallel tag sequencing reveals the complexity of anaerobic marine protistan communities 总被引:1,自引:0,他引:1
Thorsten Stoeck Anke Behnke Richard Christen Linda Amaral-Zettler Maria J Rodriguez-Mora Andrei Chistoserdov William Orsi Virginia P Edgcomb 《BMC biology》2009,7(1):72-20