The crystal structure of Mycobacterium tuberculosis adenylate kinase in complex with two molecules of ADP and Mg2+ supports an associative mechanism for phosphoryl transfer.
The crystal structure of Mycobacterium tuberculosis adenylate kinase (MtAK) in complex with two ADP molecules and Mg2+ has been determined at 1.9 A resolution. Comparison with the solution structure of the enzyme, obtained in the absence of substrates, shows significant conformational changes of the LID and NMP-binding domains upon substrate binding. The ternary complex represents the state of the enzyme at the start of the backward reaction (ATP synthesis). The structure is consistent with a direct nucleophilic attack of a terminal oxygen from the acceptor ADP molecule on the beta-phosphate from the donor substrate, and both the geometry and the distribution of positive charge in the active site support the hypothesis of an associative mechanism for phosphoryl transfer.
Bellinzoni
Marco
M
Unité de Biochimie Structurale, CNRS-URA 2185, Institut Pasteur, F-75724 Paris, France.
Haouz
Ahmed
A
Graña
Martin
M
Munier-Lehmann
Hélène
H
Shepard
William
W
Alzari
Pedro M
PM