Role of Putrescine in Regulation of the sigma^S Subunit of RNA Polymerase in Escherichia coli Cells on Transition to Stationary Phase

A. G. Tkachenko^* and M. S. Shumkov

Institute of Ecology and Genetics of Microorganisms, Ural Branch of the Russian Academy of Sciences, ul. Goleva 13, Perm 614081, Russia; fax: (3422) 646-711; E-mail: agtkachenko@ecology.psu.ru

^* To whom correspondence should be addressed.

Received July 8, 2003; Revision received January 13, 2004

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Expression of the rpoS gene encoding the sigma^S subunit of E. coli RNA polymerase was studied on transition to the stationary phase and under conditions of starvation. Polyamines, in particular putrescine, are involved in regulation of the rpoS expression by concentration-dependent stimulation at the levels of translation and stability of the protein sigma^S. The stimulatory effect of exogenous putrescine inversely depended on its content in the cell and was the most pronounced in the beginning of the exponential growth. Possible mechanisms of the polyamine effect on the rpoS expression on post-transcriptional and post-translational levels are discussed.

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KEY WORDS: polyamines, putrescine, stationary phase, starvation, rpoS, sigma^S, expression, transcription, translation, protein stability

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