Conformational changes in guanylate cyclase-activating protein 1 induced by Ca2+ and N-terminal fatty acid acylation.
Neuronal Ca(2+) sensors (NCS) are high-affinity Ca(2+)-binding proteins critical for regulating a vast range of physiological processes. Guanylate cyclase-activating proteins (GCAPs) are members of the NCS family responsible for activating retinal guanylate cyclases (GCs) at low Ca(2+) concentrations, triggering synthesis of cGMP and recovery of photoreceptor cells to the dark-adapted state. Here we use amide hydrogen-deuterium exchange and radiolytic labeling, and molecular dynamics simulations to study conformational changes induced by Ca(2+) and modulated by the N-terminal myristoyl group. Our data on the conformational dynamics of GCAP1 in solution suggest that Ca(2+) stabilizes the protein but induces relatively small changes in the domain structure; however, loss of Ca(+2) mediates a significant global relaxation and movement of N- and C-terminal domains. This model and the previously described "calcium-myristoyl switch" proposed for recoverin indicate significant diversity in conformational changes among these highly homologous NCS proteins with distinct functions.
Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4965, USA.
Tivadar
T
Orban
Grzegorz
G
Bereta
Masaru
M
Miyagi
Benlian
B
Wang
Mark R
MR
Chance
Marcelo Carlos
MC
Sousa
Krzysztof
K
Palczewski
D000215:Acylation; D000595:Amino Acid Sequence; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D041961:Deuterium Exchange Measurement; D005227:Fatty Acids / Q000737:chemistry* / Q000378:metabolism*; D051604:Guanylate Cyclase-Activating Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary
D005227:Fatty Acids; D051604:Guanylate Cyclase-Activating Proteins; D002118:Calcium