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Title: Cooperativity and allostery in cAMP-dependent activation of Protein Kinase A: Monitoring conformations of intermediates by amide hydrogen/deuterium exchange
Authors: Moorthy, B.S.
Badireddy, S.
Anand, G.S. 
Keywords: Allostery
Conformational change
Issue Date: 30-Apr-2011
Citation: Moorthy, B.S., Badireddy, S., Anand, G.S. (2011-04-30). Cooperativity and allostery in cAMP-dependent activation of Protein Kinase A: Monitoring conformations of intermediates by amide hydrogen/deuterium exchange. International Journal of Mass Spectrometry 302 (1-3) : 157-166. ScholarBank@NUS Repository.
Abstract: Amide hydrogen/deuterium exchange mass spectrometry is a powerful method both for mapping protein-protein interactions and measuring conformational dynamics of protein complexes. In this study we report its application to monitoring the stepwise process governing cAMP-dependent activation of Protein Kinase A (PKA). In the absence of cAMP, PKA exists in an inactive complex of catalytic (C) and regulatory (R) subunits. cAMP binding induces large conformational changes within the R-subunit leading to dissociation of the active C-subunit. Although crystal structures of end-point, inactive and active states are available, the molecular basis for cooperativity in cAMP-dependent activation of PKA is not clear. In this study we report application of amide hydrogen/deuterium exchange mass spectrometry on tracking the stepwise cAMP-induced conformational changes using a single point mutant (R209K) at the cyclic nucleotide binding domain (CNB)-A site. Our amide exchange results reveal that binding of one molecule of cAMP increases amide exchange in important regions within the second CNB-B domain. Increased exchange was also seen at the interface between CNB-B and the C-subunit suggesting weakening of the R-C interface without dissociation. Importantly, binding of the first molecule of cAMP greatly increases the conformational mobility/dynamics of two key regions coupling the two CNBs, the αC/C′:A and αA:B helix. We believe that the enhanced dynamics of these regions forms the basis for the positive cooperativity in the cAMP-dependent activation of PKA. In summary, our results reveal the close allosteric coupling between CNB-A and CNB-B with the C-subunit providing important molecular insights into the function of CNB-B domain. © 2010 Elsevier B.V.
Source Title: International Journal of Mass Spectrometry
ISSN: 13873806
DOI: 10.1016/j.ijms.2010.09.012
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