Microbial CellPub Date : 2015-10-12DOI: 10.15698/mic2015.11.239
Kristy L. Hentchel, J. Escalante‐Semerena
{"title":"Complex regulation of the sirtuin-dependent reversible lysine acetylation system of Salmonella enterica","authors":"Kristy L. Hentchel, J. Escalante‐Semerena","doi":"10.15698/mic2015.11.239","DOIUrl":"https://doi.org/10.15698/mic2015.11.239","url":null,"abstract":"The extensive involvement of the reversible lysine acylation (RLA) system in metabolism has attracted the attention of investigators interested in understanding the fundamentals of prokaryotic and eukaryotic cell function. Research in this area of cell physiology is diverse, ranging, among others, from probing the molecular bases of human diseases, to optimizing engineered metabolic pathways for biotechnological applications, to advancing our understanding of fundamental cellular processes. A gap of knowledge exists in our understanding of the regulatory circuitry that integrates the expression of genes encoding modifiers (i.e., acyltransferases) and demodifiers (i.e., deacylases) with the expression of genes encoding known targets of the system. Here we discuss the implications of recently reported work performed in the enteropathogen Salmonella enterica (mBio (2015) 6(4):e00891-15), which provided the first insights into the integration of the transcriptional regulation of genes encoding the RLA system with the acs gene encoding the central metabolic enzyme acetyl-CoA synthetase (Acs).","PeriodicalId":18397,"journal":{"name":"Microbial Cell","volume":"2 1","pages":"451 - 453"},"PeriodicalIF":4.6,"publicationDate":"2015-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67182864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microbial CellPub Date : 2015-01-01DOI: 10.15698/mic2015.10.231
Konstantin I Piatkov, Tri T M Vu, Cheol-Sang Hwang, Alexander Varshavsky
{"title":"Formyl-methionine as a degradation signal at the N-termini of bacterial proteins.","authors":"Konstantin I Piatkov, Tri T M Vu, Cheol-Sang Hwang, Alexander Varshavsky","doi":"10.15698/mic2015.10.231","DOIUrl":"10.15698/mic2015.10.231","url":null,"abstract":"<p><p>In bacteria, all nascent proteins bear the pretranslationally formed N-terminal formyl-methionine (fMet) residue. The fMet residue is cotranslationally deformylated by a ribosome-associated deformylase. The formylation of N-terminal Met in bacterial proteins is not strictly essential for either translation or cell viability. Moreover, protein synthesis by the cytosolic ribosomes of eukaryotes does not involve the formylation of N-terminal Met. What, then, is the main biological function of this metabolically costly, transient, and not strictly essential modification of N-terminal Met, and why has Met formylation not been eliminated during bacterial evolution? One possibility is that the similarity of the formyl and acetyl groups, their identical locations in N-terminally formylated (Nt-formylated) and Nt-acetylated proteins, and the recently discovered proteolytic function of Nt-acetylation in eukaryotes might also signify a proteolytic role of Nt-formylation in bacteria. We addressed this hypothesis about fMet-based degradation signals, termed fMet/N-degrons, using specific <i>E. coli</i> mutants, pulse-chase degradation assays, and protein reporters whose deformylation was altered, through site-directed mutagenesis, to be either rapid or relatively slow. Our findings strongly suggest that the formylated N-terminal fMet can act as a degradation signal, largely a cotranslational one. One likely function of fMet/N-degrons is the control of protein quality. In bacteria, the rate of polypeptide chain elongation is nearly an order of magnitude higher than in eukaryotes. We suggest that the faster emergence of nascent proteins from bacterial ribosomes is one mechanistic and evolutionary reason for the pretranslational design of bacterial fMet/N-degrons, in contrast to the cotranslational design of analogous Ac/N-degrons in eukaryotes.</p>","PeriodicalId":18397,"journal":{"name":"Microbial Cell","volume":"2 1","pages":"376-393"},"PeriodicalIF":4.6,"publicationDate":"2015-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4745127/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"67182824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}