Characterization of an N6 adenine methyltransferase from Helicobacter pylori strain 26695 which methylates adjacent adenines on the same strand

Kumar, Ritesh and Mukhopadhyay, Asish K and Rao, Desirazu N (2010) Characterization of an N6 adenine methyltransferase from Helicobacter pylori strain 26695 which methylates adjacent adenines on the same strand. In: FEBS Journal, 277 (7). pp. 1666-1683.

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Abstract

Genomic sequences of Helicobacter pylori strains 26695, J99, HPAGI and G27 have revealed an abundance of restriction and modification genes. hp0050, which encodes an N6 adenine DNA methyltransferase, was cloned, overexpressed and purified to near homogeneity. It recognizes the sequence 5'-GRRG-3' (where R is A or G) and, most intriguingly, methylates both adenines when R is A (5'-GAAG-3'). Kinetic analysis suggests a nonprocessive (repeated-hit) mechanism of methylation in which HP0050 methyltransferase methylates one adenine at a time in the sequence 5'-GAAG-3'. This is the first report of an N6 adenine DNA methyltransferase that methylates two adjacent residues on the same strand. Interestingly, HP0050 homologs from two clinical strains of H. pylori (PG227 and 128) methylate only 5'-GAGG-3' compared with 5'-GRRG-3' in strain 26695. HP0050 methyltransferase is highly conserved as it is present in more than 90% of H. pylori strains. Inactivation of hp0050 in strain PG227 resulted in poor growth, suggesting its role in the biology of H. pylori. Collectively, these findings provide impetus for exploring the role(s) of this conserved DNA methyltransferase in the cellular processes of H. pylori.

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:	base flipping; DNA methyltransferase; Helicobacter pylori; S-adenosyl-l-methionine; site-directed mutagenesis
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	10 Jun 2010 09:17
Last Modified:	19 Sep 2010 05:59
URI:	http://eprints.iisc.ac.in/id/eprint/27039

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