Intrinsic DNA Distortion of the Bacteriophage Mu momP1 Promoter Is a Negative Regulator of Its Transcription

Basak, Shashwati and Olsen, Lars and Hattman, Stanley and Nagaraja, Valakunja (2001) Intrinsic DNA Distortion of the Bacteriophage Mu momP1 Promoter Is a Negative Regulator of Its Transcription. In: The Journal of Biological Chemistry, 276 (23). pp. 19836-19844.

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Abstract

The momP1 promoter of the bacteriophage Mu mom operon is an example of a weak promoter. It contains a 19-base pair suboptimal spacer between the 235 (ACCACA) and 210 (TAGAAT) hexamers. Escherichia coli RNA polymerase is unable to bind tomomP1 on its own.DNAdistortion caused by the presence of a run of six T nucleotides overlapping the 5* end of the 210 element might prevent RNA polymerase from binding to momP1. To investigate the influence of the T6 run on momP1 expression, defined substitution mutations were introduced by site-directed mutagenesis.In vitro probing experiments with copper phenanthroline ((OP)2Cu) and DNase I revealed distinct differences in cleavage patterns among the various mutants; in addition, compared with the wild type, the mutants showed an increase (variable) in momP1 promoter activity in vivo. Promoter strength analyses were in agreement with the ability of these mutants to form open complexes as well as to produce momP1-specific transcripts. No significant role is tributed to the overlapping and divergently organized promoter, momP2, in the expression of momP1 activity, as determined by promoter disruption analysis. These data support the view that an intrinsic DNA distortion in the spacer region of momP1 acts in cis as a negative element in mom operon transcription. This is a novel mechanism of regulation of toxic gene expression.

Item Type:	Journal Article
Publication:	The Journal of Biological Chemistry
Publisher:	The American Society for Biochemistry and Molecular Biology
Keywords:	Intrinsic DNA Distortion;momP1 promoter
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	26 Jul 2004
Last Modified:	19 Sep 2010 04:14
URI:	http://eprints.iisc.ac.in/id/eprint/1152

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