TY - JOUR
T1 - Modeling of the complex between transducin and photoactivated rhodopsin, a prototypical G-protein-coupled receptor
AU - Nikiforovich, Gregory V.
AU - Taylor, Christina M.
AU - Marshall, Garland R.
PY - 2007/4/24
Y1 - 2007/4/24
N2 - Obtaining a reliable 3D model for the complex formed by photoactivated rhodopsin (R*) and its G-protein, transducin (Gtαβγ), would significantly benefit the entire field of structural biology of G-protein-coupled receptors (GPCRs). In this study, we have performed extensive configurational sampling for the isolated C-terminal fragment of the α-subunit of transducin, Gtα 340-350, within cavities of photoactivated rhodopsin formed by different energetically feasible conformations of the intracellular loops. Our results suggested a new 3D model of the rhodopsin-transducin complex that fully satisfied all available experimental data on site-directed mutagenesis of rhodopsin and Gtαβγ as well as data from disulfide-linking experiments. Importantly, the experimental data were not used as a priori constraints in model building. We performed a thorough comparison of existing computational models of the rhodopsin-transducin complex with each other and with current experimental data. It was found that different models suggest interactions with different molecules in the rhodopsin oligomer, that providing valuable guidance in design of specific novel experimental studies of the R*- Gtαβγ complex. Finally, we demonstrated that the isolated Gtα 340-350 fragment does not necessarily bind rhodopsin in the same binding mode as the same segment in intact Gtα.
AB - Obtaining a reliable 3D model for the complex formed by photoactivated rhodopsin (R*) and its G-protein, transducin (Gtαβγ), would significantly benefit the entire field of structural biology of G-protein-coupled receptors (GPCRs). In this study, we have performed extensive configurational sampling for the isolated C-terminal fragment of the α-subunit of transducin, Gtα 340-350, within cavities of photoactivated rhodopsin formed by different energetically feasible conformations of the intracellular loops. Our results suggested a new 3D model of the rhodopsin-transducin complex that fully satisfied all available experimental data on site-directed mutagenesis of rhodopsin and Gtαβγ as well as data from disulfide-linking experiments. Importantly, the experimental data were not used as a priori constraints in model building. We performed a thorough comparison of existing computational models of the rhodopsin-transducin complex with each other and with current experimental data. It was found that different models suggest interactions with different molecules in the rhodopsin oligomer, that providing valuable guidance in design of specific novel experimental studies of the R*- Gtαβγ complex. Finally, we demonstrated that the isolated Gtα 340-350 fragment does not necessarily bind rhodopsin in the same binding mode as the same segment in intact Gtα.
UR - http://www.scopus.com/inward/record.url?scp=34247550299&partnerID=8YFLogxK
U2 - 10.1021/bi700185p
DO - 10.1021/bi700185p
M3 - Article
C2 - 17397191
AN - SCOPUS:34247550299
VL - 46
SP - 4734
EP - 4744
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 16
ER -