Type III restriction-modification enzymes: a historical perspective

Rao, Desirazu N and Dryden, David TF and Bheemanaik, Shivakumara (2014) Type III restriction-modification enzymes: a historical perspective. In: NUCLEIC ACIDS RESEARCH, 42 (1). pp. 45-55.

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Abstract

Restriction endonucleases interact with DNA at specific sites leading to cleavage of DNA. Bacterial DNA is protected from restriction endonuclease cleavage by modifying the DNA using a DNA methyltransferase. Based on their molecular structure, sequence recognition, cleavage position and cofactor requirements, restriction-modification (R-M) systems are classified into four groups. Type III R-M enzymes need to interact with two separate unmethylated DNA sequences in inversely repeated head-to-head orientations for efficient cleavage to occur at a defined location (25-27 bp downstream of one of the recognition sites). Like the Type I R-M enzymes, Type III R-M enzymes possess a sequence-specific ATPase activity for DNA cleavage. ATP hydrolysis is required for the long-distance communication between the sites before cleavage. Different models, based on 1D diffusion and/or 3D-DNA looping, exist to explain how the long-distance interaction between the two recognition sites takes place. Type III R-M systems are found in most sequenced bacteria. Genome sequencing of many pathogenic bacteria also shows the presence of a number of phase-variable Type III R-M systems, which play a role in virulence. A growing number of these enzymes are being subjected to biochemical and genetic studies, which, when combined with ongoing structural analyses, promise to provide details for mechanisms of DNA recognition and catalysis.

Item Type:	Journal Article
Publication:	NUCLEIC ACIDS RESEARCH
Publisher:	OXFORD UNIV PRESS
Additional Information:	Copyright for this article belongs to the OXFORD UNIV PRESS, GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	04 Apr 2014 08:28
Last Modified:	04 Apr 2014 08:28
URI:	http://eprints.iisc.ac.in/id/eprint/48771

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