Chemistry and biology of DNA methyltransferases

Ahmad, I and Rao, DN (1996) Chemistry and biology of DNA methyltransferases. In: Critical Reviews in Biochemistry and Molecular Biology, 31 (5-6). pp. 361-380.

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Abstract

Recognition of a specific DNA sequence by a protein is probably the best example of macromolecular interactions leading to various events. It is a prerequisite to understanding the basis of protein-DNA interactions to obtain a better insight into fundamental processes such as transcription, replication, repair, and recombination. DNA methyltransferases with varying sequence specificities provide an excellent model system for understanding the molecular mechanism of specific DNA recognition. Sequence comparison of cloned genes, along with mutational analyses and recent crystallographic studies, have clearly defined the functions of various conserved motifs. These enzymes access their target base in an elegant manner by flipping it out of the DNA double helix. The drastic protein-induced DNA distortion, first reported for HhaI DNA methyltransferase, appears to be a common mechanism employed by various proteins that need to act on bases. A remarkable feature of the catalytic mechanism of DNA (cytosine-5) methyltransferases is the ability of these enzymes to induce deamination of the target cytosine in the absence of S-adenosyl-L-methionine or its analogs. The enzyme-catalyzed deamination reaction is postulated to be the major cause of mutational hotspots at CpG islands responsible for various human genetic disorders. Methylation of adenine residues in Escherichia coli is known to regulate various processes such as transcription, replication, repair, recombination, transposition, and phage packaging.

Item Type:	Journal Article
Publication:	Critical Reviews in Biochemistry and Molecular Biology
Publisher:	Informa plc
Additional Information:	Copyright of this article belongs to Informa plc.
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	27 Jan 2010 10:28
Last Modified:	19 Sep 2010 05:51
URI:	http://eprints.iisc.ac.in/id/eprint/24675

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