[Regulation of expression of bacterial genes in the absence of active cell growth].

Global changes in cell physiology and metabolism take place in bacterial cells entering the stationary phase. The processes that ensure cell survival under adverse environmental conditions are activated, and cells with an improved resistance to many stress factors are formed as a result of the general stress response. The review considers the molecular mechanisms of cell differentiation in Gram-negative bacteria (exemplified by Escherichia coli) upon deceleration or complete suppression of cell growth, including changes in all steps of gene expression. The transition to the stationary phase is accompanied by DNA compaction, which is due to qualitative and quantitative changes in the protein composition of the nucleoid. Changes in the translation machinery under these conditions include the formation of functionally inactive 100S ribosome dimers with participation of RMF. Dramatic changes are observed in the transcription machinery: while the general level of gene expression decreases, activation or induction is characteristic of many genes and operons that are silent in actively growing cells. The key role in stationary stage-associated regulation of gene transcription is played by the sigmaS subunit of RNA polymerase. Expression of the rpoS gene, which codes for sigmaS, is regulated by an intricate multicomponent regulatory network, which functions at the levels of transcription of the rpoS gene, translation of the rpoS mRNA, and proteolysis of sigmaS. In addition, some issues of selection of sigmaS for transcription initiation and the roles of other factors in regulating gene expression in cells with decelerated or completely suppressed growth are discussed. Data are presented on the role of quorum-sensing systems in regulating the processes that occur at a high density of a bacterial population.