A Comparative Kinetic and Thermodynamic Perspective of the sigma-Competition Model in Escherichia coli

Ganguly, Abantika and Chatterji, Dipankar (2012) A Comparative Kinetic and Thermodynamic Perspective of the sigma-Competition Model in Escherichia coli. In: BIOPHYSICAL JOURNAL, 103 (6). pp. 1325-1333. (In Press)

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Abstract

Transcription is the most fundamental step in gene expression in any living organism. Various environmental cues help in the maturation of core RNA polymerase (RNAP; alpha(2)beta beta'omega) with different sigma-factors, leading to the directed recruitment of RNAP to different promoter DNA sequences. Thus it is essential to determine the sigma-factors that affect the preferential partitioning of core RNAP among various a-actors, and the role of sigma-switching in transcriptional gene regulation. Further, the macromolecular assembly of holo RNAP takes place in an extremely crowded environment within a cell, and thus far the kinetics and thermodynamics of this molecular recognition process have not been well addressed. In this study we used a site-directed bioaffinity immobilization method to evaluate the relative binding affinities of three different Escherichia coli sigma-factors to the same core RNAP with variations in temperature and ionic strength while emulating the crowded cellular milieu. Our data indicate that the interaction of core RNAP-sigma is susceptible to changes in external stimuli such as osmolytic and thermal stress, and the degree of susceptibility varies among different sigma-factors. This allows for a reversible sigma-switching from housekeeping factors to alternate sigma-factors when the organism senses a change in its physiological conditions.

Item Type:	Journal Article
Publication:	BIOPHYSICAL JOURNAL
Publisher:	CELL PRESS
Additional Information:	Copyright for this article belongs to CELL PRESS
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited:	11 Jan 2013 09:13
Last Modified:	11 Jan 2013 09:13
URI:	http://eprints.iisc.ac.in/id/eprint/45268

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