Asymmetric DNA methylation by dirneric EcoP15I DNA methyltransferase

Urulangodi, Madhusoodanan and Dhanaraju, Rajkumar and Gupta, Kanchan and Roy, Rajendra P and Bujnicki, Janusz M and Rao, Desirazu N (2016) Asymmetric DNA methylation by dirneric EcoP15I DNA methyltransferase. In: BIOCHIMIE, 128 . pp. 70-82.

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Abstract

EcoP15I DNA methyltransferase (M.EcoP15I) recognizes short asymmetric sequence, 5'-CAGCAG-3', and methylates the second adenine only on one strand of the double-stranded DNA (dsDNA). In vivo, this methylation is sufficient to protect the host DNA from cleavage by the cognate restriction endonuclease, R.EcoP15I, because of the stringent cleavage specificity requirements. Biochemical and structural characterization support the notion that purified M.EcoP15I exists and functions as dimer. However, the exact role of dimerization in M.EcoP15I reaction mechanism remains elusive. Here we engineered M.EcoP15I to a stable monomeric form and studied the role of dimerization in enzyme catalyzed methylation reaction. While the monomeric form binds single-stranded DNA (ssDNA) containing the recognition sequence it is unable to methylate it. Further we show that, while the monomeric form has AdoMet binding and Mg2+ binding motifs intact, optimal dsDNA binding required for methylation is dependent on dimerization. Together, our biochemical data supports a unique subunit organization for M.EcoP15I to catalyze the methylation reaction. (C) 2016 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM). All rights reserved.

Item Type:	Journal Article
Publication:	BIOCHIMIE
Additional Information:	Copy right for this article belongs to the ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 23 RUE LINOIS, 75724 PARIS, FRANCE
Department/Centre:	Division of Biological Sciences > Biochemistry
Date Deposited:	03 Dec 2016 09:24
Last Modified:	03 Dec 2016 09:24
URI:	http://eprints.iisc.ac.in/id/eprint/55348

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