NMR identification of transient complexes critical to adenylate kinase catalysis
2007 (English)In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 129, no 45, 14003-12 p.Article in journal (Refereed) Published
A fundamental question in protein chemistry is how the native energy landscape of enzymes enables efficient catalysis of chemical reactions. Adenylate kinase is a small monomeric enzyme that catalyzes the reversible conversion of AMP and ATP into two ADP molecules. Previous structural studies have revealed that substrate binding is accompanied by large rate-limiting spatial displacements of both the ATP and AMP binding motifs. In this report a solution-state NMR approach was used to probe the native energy landscape of adenylate kinase in its free form, in complex with its natural substrates, and in the presence of a tight binding inhibitor. Binding of ATP induces a dynamic equilibrium in which the ATP binding motif populates both the open and the closed conformations with almost equal populations. A similar scenario is observed for AMP binding, which induces an equilibrium between open and closed conformations of the AMP binding motif. These ATP- and AMP-bound structural ensembles represent complexes that exist transiently during catalysis. Simultaneous binding of AMP and ATP is required to force both substrate binding motifs to close cooperatively. In addition, a previously unknown unidirectional energetic coupling between the ATP and AMP binding sites was discovered. On the basis of these and previous results, we propose that adenylate kinase belongs to a group of enzymes whose substrates act to shift pre-existing equilibria toward catalytically active states.
Place, publisher, year, edition, pages
2007. Vol. 129, no 45, 14003-12 p.
IdentifiersURN: urn:nbn:se:umu:diva-16865DOI: doi:10.1021/ja075055gPubMedID: 17935333OAI: oai:DiVA.org:umu-16865DiVA: diva2:156538
Web Release Date: October 13, 20072007-12-112007-12-112010-10-15Bibliographically approved