DNA-induced conformational changes in RecA protein. Evidence for structural heterogeneity among nucleoprotein filaments and implications for homologous pairing

Kumar, KA and Mahalakshmi, S and Muniyappa, K (1993) DNA-induced conformational changes in RecA protein. Evidence for structural heterogeneity among nucleoprotein filaments and implications for homologous pairing. In: Journal of General Microbiology, 268 (35). pp. 26162-26170.

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Abstract

We have used circular dichroism as a probe to characterize the solution conformational changes in RecA protein upon binding to DNA. This approach revealed that RecA protein acquires significant amounts of alpha-helix upon interaction with DNA. These observations, consistent with the data from crystal structure (Story, R. M., Weber, I., and Steitz, T. (1992) Nature 355, 318-325), support the notion that some basic domains including the DNA binding motifs of RecA protein are unstructured and might contribute to the formation of alpha-helix. A comparison of nucleoprotein filaments comprised of RecA protein and a variety of DNA substrates revealed important structural heterogeneity. The most significant difference was observed with poly(dG). poly(dC) and related polymers, rich in GC sequences, which induced minimal amounts of alpha-helix in RecA protein. The magnitude of induction of alpha-helix in RecA protein, which occurred concomitant with the production of ternary complexes, was 2-fold higher with homologous than heterologous duplex DNA. Most importantly, the stimulation of ATP hydrolysis by high salt coincided with that of the induction of alpha-helix in RecA protein. These conformational differences provide a basis for thinking about the biochemical and structural transitions that RecA protein experiences during the formal steps of presynapsis, recognition, and alignment of homologous sequences.

Item Type:	Journal Article
Publication:	Journal of General Microbiology
Publisher:	Society for General Microbiology
Additional Information:	Copyright of this article belongs to Society for General Microbiology.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	19 Feb 2010 06:59
Last Modified:	19 Sep 2010 05:55
URI:	http://eprints.iisc.ac.in/id/eprint/25675

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