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Functional characterization of the DNA mismatch binding protein MutS from Haemophilus influenzae

Joseph, Nimesh and Duppatla, Viswanadham and Rao, Desirazu N (2005) Functional characterization of the DNA mismatch binding protein MutS from Haemophilus influenzae. In: Biochemical and Biophysical Research Communications, 334 (3). pp. 891-900.

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Abstract

This investigation demonstrates DNA mismatch repair activity in Haemophilus influenzae cell free extracts. The mutS gene as well as purified protein of H. influenzae restored repair activity incomplementation assays performed with mutS deficient Escherichia colistrain. The difference in affinity for GT and AC mismatched bases by H.influenzae Mats was reflected in the efficiency with which these DNA heteroduplexes were repaired in vitro, with GT being repaired well and AC the least. Unlike E. coli MutS, the H. influenzae homology failed to give protein-DNA complex with homoduplex DNA. Interestingly, MutS was found to bind single-stranded DNA but With lesser affinity as compared to heteroduplex DNA. Apart from the nucleotide- and DNA-mediated conformational transitions. as monitored by circular dichroism and limited proteolysis, our data suggest a functional role when H.influnezae MutS encounters single-stranded DNA during exonucleolytic step of DNA repair process. We propose that, conformational changes in H. influenzae MutS not only modulate mismatch recognition but also trigger some of the down stream processes involved in the DNA mismatch repair process.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to Elsevier.
Keywords: Haemophilus influenzae;DNA mismatch repair;MutS;ATPase;DNA binding;Limited proteolysis;Electrophoretic mobility shift;In vivo complementation;In vitro complementation;Circular dichroism;Heteroduplex DNA
Department/Centre: Division of Biological Sciences > Biochemistry
Date Deposited: 17 Oct 2005
Last Modified: 19 Sep 2010 04:20
URI: http://eprints.iisc.ernet.in/id/eprint/3823

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