Mechanism of Mg2+-Accompanied Product Release in Sugar Nucleotidyltransferases.

Neha, Vithani and Pravin Kumar, A. J. and Sunil Kumar, Verma and Ravi, Tripathi and Shalini, A. and Nishanth, N. Nair and Balaji, Prakash (2018) Mechanism of Mg2+-Accompanied Product Release in Sugar Nucleotidyltransferases. Structure, 26. pp. 459-466.

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Abstract

The nucleotidyl transfer reaction, catalyzed by sugar nucleotidyltransferases (SNTs), is assisted by two active site Mg2+ ions. While studying this reaction using X-ray crystallography, we captured snapshots of the pyrophosphate (product) as it exits along a pocket. Surprisingly, one of the active site Mg2+ ions remains coordinated to the exiting pyrophosphate. This hints at the participation of Mg2+ in the process of product release, besides its role in catalyzing nucleotidyl transfer. These observations are further supported by enhanced sampling molecular dynamics simulations. Free energy computations suggest that the product release is likely to be rate limiting in SNTs, and the origin of the high free energy barrier for product release could be traced back to the ‘‘slow’’ conformational change of an Arg residue at the exit end of the pocket. These results establish a dual role for Mg2+, and propose a general mechanism of product release during the nucleotidyl transfer by SNTs.

Item Type:	Article
Uncontrolled Keywords:	Sugar nucleotidyltransferases, Mg2+
Subjects:	500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 31 Sugar Chemistry
Divisions:	Molecular Nutrition
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	12 Jul 2018 05:52
Last Modified:	12 Jul 2018 05:52
URI:	http://ir.cftri.res.in/id/eprint/13595

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