Mutations in hpyAVIBM, C5 cytosine DNA methyltransferase from Helicobacter pylori result in relaxed specificity

Kumar, Ritesh and Sabareesh, Varatharajan and Mukhopadhyay, Asish K and Rao, Desirazu N (2012) Mutations in hpyAVIBM, C5 cytosine DNA methyltransferase from Helicobacter pylori result in relaxed specificity. In: FEBS Journal, 279 (6). pp. 1080-1092.

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Abstract

The genome of Helicobacter pylori is rich in restrictionmodification (RM) systems. Approximately 4% of the genome codes for components of RM systems. hpyAVIBM, which codes for a phase-variable C5 cytosine methyltransferase (MTase) from H. pylori, lacks a cognate restriction enzyme. Over-expression of M.HpyAVIB in Escherichia coli enhances the rate of mutations. However, when the catalytically inactive F9N or C82W mutants of M.HpyAVIB were expressed in E. coli, mutations were not observed. The M.HpyAVIB gene itself was mutated to give rise to different variants of the MTase. M.HpyAVIB variants were purified and differences in kinetic properties and specificity were observed. Intriguingly, purified MTase variants showed relaxed substrate specificity. Homologues of hpyAVIBM homologues amplified and sequenced from different clinical isolates showed similar variations in sequence. Thus, hpyAVIBM presents an interesting example of allelic variations in H. pylori where changes in the nucleotide sequence result in proteins with new properties.

Item Type:	Journal Article
Publication:	FEBS Journal
Publisher:	John Wiley and Sons
Additional Information:	Copyright of this article belongs to John Wiley and Sons.
Keywords:	DNA methyltransferase;EcoDam;Helicobacter pylori;mismatch repair pathway;mutations
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	12 May 2012 10:29
Last Modified:	12 May 2012 10:39
URI:	http://eprints.iisc.ac.in/id/eprint/44400

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