Substrate specificity determinants of class III nucleotidyl cyclases

Bharambe, Nikhil G and Barathy, Deivanayaga V and Syed, Wajeed and Visweswariah, Sandhya S and Colaco, Melwin and Misquith, Sandra and Suguna, Kaza (2016) Substrate specificity determinants of class III nucleotidyl cyclases. In: FEBS JOURNAL, 283 (20). pp. 3723-3738.

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Abstract

The two second messengers in signalling, cyclic AMP and cyclic GMP, are produced by adenylyl and guanylyl cyclases respectively. Recognition and discrimination of the substrates ATP and GTP by the nucleotidyl cyclases are vital in these reactions. Various apo-, substrate- or inhibitor-bound forms of adenylyl cyclase (AC) structures from transmembrane and soluble ACs have revealed the catalytic mechanism of ATP cyclization reaction. Previously reported structures of guanylyl cyclases represent ligand-free forms and inactive open states of the enzymes and thus do not provide information regarding the exact mode of substrate binding. The structures we present here of the cyclase homology domain of a class III AC from Mycobacterium avium (Ma1120) and its mutant in complex with ATP and GTP in the presence of calcium ion, provide the structural basis for substrate selection by the nucleotidyl cyclases at the atomic level. Precise nature of the enzyme-substrate interactions, novel modes of substrate binding and the ability of the binding pocket to accommodate diverse conformations of the substrates have been revealed by the present crystallographic analysis. This is the first report to provide structures of both the nucleotide substrates bound to a nucleotidyl cyclase. Database Coordinates and structure factors have been deposited in the Protein Data Bank with accession numbers: 5D15 (Ma1120(CHD)+ATP.Ca2+), 5D0E (Ma1120(CHD)+GTP.Ca2+), 5D0H (Ma1120(CHD)(KDA -> EGY)+ATP.Ca2+), 5D0G (Ma1120(CHD)(KDA -> EGY)+GTP.Ca2+). Enzymes Adenylyl cyclase (EC number: 4.6.1.1).

Item Type:	Journal Article
Publication:	FEBS JOURNAL
Additional Information:	Copy right for this article belongs to the WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre:	Division of Biological Sciences > Molecular Biophysics Unit Division of Biological Sciences > Molecular Reproduction, Development & Genetics
Date Deposited:	30 Dec 2016 07:09
Last Modified:	30 Dec 2016 07:09
URI:	http://eprints.iisc.ac.in/id/eprint/55646

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