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Journal of Applied Genetics 48(3), 2007, pp. 281-294

Mechanisms of physiological regulation of RNA synthesis in bacteria: new discoveries breaking old schemes

Agnieszka Szalewska-Palasz, Grzegorz Wegrzyn, Alicja Wegrzyn

Abstract: Although in bacterial cells all genes are transcribed by RNA polymerase, there are 2 additional enzymes capable of catalyzing RNA synthesis: poly(A) polymerase I, which adds poly(A) residues to transcripts, and primase, which produces primers for DNA replication. Mechanisms of actions of these 3 RNA-synthesizing enzymes were investigated for many years, and schemes of their regulations have been proposed and generally accepted. Nevertheless, recent discoveries indicated that apart from well-understood mechanisms, there are additional regulatory processes, beyond the established schemes, which allow bacterial cells to respond to changing environmental and physiological conditions. These newly discovered mechanisms, which are discussed in this review, include: (i) specific regulation of gene expression by RNA polyadenylation, (ii) control of DNA replication by interactions of the starvation alarmones, guanosine pentaphosphate and guanosine tetraphosphate, (p)ppGpp, with DnaG primase, (iii) a role for the DksA protein in ppGpp-mediated regulation of transcription, (iv) allosteric modulation of the RNA polymerase catalytic reaction by specific inhibitors of transcription, rifamycins, (v) stimulation of transcription initiation by proteins binding downstream of the promoter sequences, and (vi) promoter-dependent control of transcription antitermination efficiency.

Key words: DNA replication, primase activity, RNA polyadenylation, RNA polymerase, RNA synthesis, transcription regulation.

Correspondence: A. Szalewska-Palasz, Department of Molecular Biology, University of Gdansk, Kladki 24, 80-822 Gdansk, Poland, e-mail:

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