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Distinct and Contrasting Transcription Initiation Patterns at Mycobacterium tuberculosis Promoters

Tare, Priyanka and China, Arnab and Nagaraja, Valakunja (2012) Distinct and Contrasting Transcription Initiation Patterns at Mycobacterium tuberculosis Promoters. In: PLos One, 7 (9).

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Official URL: http://dx.doi.org/10.1371/journal.pone.0043900

Abstract

Although sequencing of Mycobacterium tuberculosis genome lead to better understanding of transcription units and gene functions, interactions occurring during transcription initiation between RNA polymerase and promoters is yet to be elucidated. Different stages of transcription initiation include promoter specific binding of RNAP, isomerization, abortive initiation and promoter clearance. We have now analyzed these events with four promoters of M. tuberculosis viz. P-gyrB1, P-gyrR, P-rrnPCL1 and P-metU. The promoters differed from each other in their rates of open complex formation, decay, promoter clearance and abortive transcription. The equilibrium binding and kinetic studies of various steps revealed distinct rate limiting events for each of the promoter, which also differed markedly in their characteristics from the respective promoters of Mycobacterium smegmatis. Surprisingly, the transcription at gyr promoter was enhanced in the presence of initiating nucleotides and decreased in the presence of alarmone, pppGpp, a pattern typically seen with rRNA promoters studied so far. The gyr promoter of M. smegmatis, on the other hand, was not subjected to pppGpp mediated regulation. The marked differences in the transcription initiation pathway seen with rrn and gyr promoters of M. smegmatis and M. tuberculosis suggest that such species specific differences in the regulation of expression of the crucial housekeeping genes could be one of the key determinants contributing to the differences in growth rate and lifestyle of the two organisms. Moreover, the distinct rate limiting steps during transcription initiation of each one of the promoters studied point at variations in their intracellular regulation.

Item Type: Journal Article
Additional Information: Copyright for this article is belongs to Public Library of Science.
Keywords: RIBOSOMAL-RNA SYNTHESIS;ESCHERICHIA-COLI K-12; GENE-REGULATION;POLYMERASE;DNA;PATHWAY;COMPLEX;OPERON; RESISTANCE;MECHANISM
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 07 Dec 2012 08:41
Last Modified: 07 Dec 2012 08:41
URI: http://eprints.iisc.ernet.in/id/eprint/45200

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