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Mol Genet Genomics. 2007 Jul;278(1):75-84. Epub 2007 Mar 24.

Autogenous regulation of Escherichia coli polynucleotide phosphorylase during cold acclimation by transcription termination and antitermination.

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Dipartimento di Scienze biomolecolari e Biotecnologie, UniversitĂ  degli Studi di Milano, Via Celoria 26, 20133, Milano, Italy.


Adaptation of Escherichia coli at low temperature implicates a drastic reprogramming of gene expression patterns. Mechanisms operating downstream of transcription initiation, such as control of transcription termination, mRNA stability and translatability, play a major role in controlling gene expression in the cold acclimation phase. It was previously shown that Rho-dependent transcription termination within pnp, the gene encoding polynucleotide phosphorylase (PNPase), was suppressed in pnp nonsense mutants, whereas it was restored by complementation with wild type allele. Using a tRNA gene as a reporter and the strong Rho-dependent transcription terminator t ( imm ) of bacteriophage P4 as a tester, here we show that specific sites in the 5'-untranslated region of pnp mRNA are required for PNPase-sensitive cold-induced suppression of Rho-dependent transcription termination. We suggest that suppression of Rho-dependent transcription termination within pnp and its restoration by PNPase is an autogenous regulatory circuit that modulates pnp expression during cold acclimation.

[Indexed for MEDLINE]

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