title: Prediction of protein-protein interfaces on G-protein beta subunits reveals a novel phospholipase C beta2 binding domain.
abstract: Gbeta subunits from heterotrimeric G-proteins (guanine nucleotide-binding proteins) directly bind diverse proteins, including effectors and regulators, to modulate a wide array of signaling cascades. These numerous interactions constrained the evolution of the molecular surface of Gbeta. Although mammals contain five Gbeta genes comprising two classes (Gbeta1-like and Gbeta5-like), plants and fungi have a single ortholog, and organisms such as Caenorhabditis elegans and Drosophila melanogaster contain one copy from each class. A limited number of crystal structures of complexes containing Gbeta subunits and complementary biochemical data highlight specific sites within Gbetas needed for protein interactions. It is difficult to determine from these interaction sites what, if any, additional regions of the Gbeta molecular surface comprise interaction interfaces essential to Gbeta's role as a nexus in numerous signaling cascades. We used a comparative evolutionary approach to identify five known and eight previously unknown putative interfaces on the surface of Gbeta. We show that one such novel interface occurs between Gbeta and phospholipase C beta2 (PLC-beta2), a mammalian Gbeta interacting protein. Substitutions of residues within this Gbeta-PLC-beta2 interface reduce the activation of PLC-beta2 by Gbeta1, confirming that our de novo comparative evolutionary approach predicts previously unknown Gbeta-protein interfaces. Similarly, we hypothesize that the seven remaining untested novel regions contribute to putative interfaces for other Gbeta interacting proteins. Finally, this comparative evolutionary approach is suitable for application to any protein involved in a significant number of protein-protein interactions.
authors: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
authors: Erin J
authors: EJ
authors: Friedman
authors: Brenda R S
authors: BR
authors: Temple
authors: Stephanie N
authors: SN
authors: Hicks
authors: John
authors: J
authors: Sondek
authors: Corbin D
authors: CD
authors: Jones
authors: Alan M
authors: AM
authors: Jones
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D017173:Caenorhabditis elegans / Q000378:metabolism; D002522:Chlorocebus aethiops; D019295:Computational Biology; D004331:Drosophila melanogaster / Q000378:metabolism; D019143:Evolution, Molecular; D005544:Forecasting; D044387:GTP-Binding Protein beta Subunits / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D054799:Phospholipase C beta / Q000378:metabolism*; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping / Q000379:methods; D015003:Yeasts / Q000378:metabolism
chemical_list: D044387:GTP-Binding Protein beta Subunits; D054799:Phospholipase C beta