Dynamic binding of PKA regulatory subunit RI alpha.
Recent crystal structures have revealed that regulatory subunit RIalpha of PKA undergoes a dramatic conformational change upon complex formation with the catalytic subunit. Molecular dynamics studies were initiated to elucidate the contributions of intrinsic conformational flexibility and interactions with the catalytic subunit in formation and stabilization of the complex. Simulations of a single RIalpha nucleotide binding domain (NBD), missing cAMP, showed that its C helix spontaneously occupies two distinct conformations: either packed against the nucleotide binding domain as in its cAMP bound structure, or extended into an intermediate form resembling that of the holoenzyme structure. C helix extension was not seen in a simulation of either RIalpha NBD. In a model complex containing both NBDs and the catalytic subunit, well-conserved residues at the interface between the NBDs in the cAMP bound form were found to stabilize the complex through contacts with the catalytic subunit. The model structure is consistent with available experimental data.
Gullingsrud
Justin
J
Department of Chemistry and Biochemistry, University of California, San Diego, California 92093, USA. jgulling@mccammon.ucsd.edu
Kim
Choel
C
Taylor
Susan S
SS
McCammon
J Andrew
JA
D003198:Computer Simulation; D000242:Cyclic AMP / Q000378:metabolism; D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; D017868:Cyclic AMP-Dependent Protein Kinases / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry* / Q000378:metabolism*
D054756:Cyclic AMP-Dependent Protein Kinase RIalpha Subunit; C517834:PRKAR1A protein, human; D021122:Protein Subunits; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases