Starvation-inducible loci of Salmonella typhimurium: regulation and roles in starvation-survival
| Autor: | C L Cubitt, Michael P. Spector |
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| Rok vydání: | 1992 |
| Předmět: |
Genetics
Salmonella typhimurium Cell signaling Gene Expression Locus (genetics) Biology biology.organism_classification Microbiology Molecular biology Enterobacteriaceae Receptors Cyclic AMP Gene product Kinetics cAMP receptor protein Genes Bacterial Gene expression Mutation biology.protein Cyclic AMP Epistasis Anaerobiosis Cloning Molecular Molecular Biology Psychological repression Alleles |
| Zdroj: | Molecular microbiology. 6(11) |
| ISSN: | 0950-382X |
| Popis: | Summary Four starvation-inducible loci (stiA, stiB, stiC, and stiE) of Salmonella typhimurium have been extensively characterized as to their genetic and physiologic regulation, and their roles in survival during prolonged simultaneous phosphate (P)-, carbon (C)-and nitrogen (N)-starvation (PCN-starvation). Strains of S. typhimurium LT-2, isogenic with the exception of lacking either the stiA, stiB or stiC locus, died off more quickly and survived at much reduced levels compared with their wild-type parent. When certain sti mutations were combined in the same strain, we found that viability of these cultures declined even more rapidly, and starvation-survival was affected to leveis over-and-above the additive effects of each individual mutation, indicating an epistatic relationship between these loci. All four sti loci were, directly or indirectly, under negative control by the crp gene product (cAMP receptor protein, CRP). With the exception of stiB, all were similarly regulated by the cya gene product (i.e., cAMP). This suggests that CRP acts alone, or with a signal molecule other than cAMP, to cause repression of the stiB locus. In addition, all four loci are under positive regulation by the relA gene product (i.e., ppGpp) during C- or N-starvation, but not P-starvation. Since not all relA-depen-dent sti loci are induced during both C- and N-starvation, we propose that two separate ppGpp-dependent pathways function during C-starvation and N-starvation, respectively. Possible models for separate P-, C-and N-starvation-induction pathways are discussed. |
| Databáze: | OpenAIRE |
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