Conformational movement of F251 contributes to the molecular mechanism of constitutive activation in the C5a receptor.
The activation mechanism of G-protein-coupled receptors triggered upon binding of a ligand represents a very important 'conformational switch' in the biological array of signal transduction. However, the molecular and functional details for this activation switch remain unknown. Random saturation mutagenesis data on the complement factor 5a receptor has provided a large data set of mutants including several constitutively active mutants. In the present study, we employed computational modeling to rationalize the constitutive activity for two constitutively active mutants, NQ (I124N/L127Q) and F251A, and we then made predictions for a series of mutants that either promote or constrain constitutive activity. Biological testing of the site-directed mutants confirmed most of the predictions of the computational modeling. These results support a molecular mechanism of constitutive activity in complement factor 5a receptor mutants that is associated with conformational changes in a network of residues neighboring F251 as the focal point of origin.
Sen
Saurabh
S
Division of Endocrinology, Metabolism and Lipid Research, Department of Internal Medicine, Washington University School of Medicine, Box 8127, St Louis, MO 63110, USA.
Baranski
Thomas J
TJ
Nikiforovich
Gregory V
GV
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D044087:Receptor, Anaphylatoxin C5a / Q000819:agonists* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D044087:Receptor, Anaphylatoxin C5a