title: Structural modeling of protein interactions by analogy: application to PSD-95.
abstract: We describe comparative patch analysis for modeling the structures of multidomain proteins and protein complexes, and apply it to the PSD-95 protein. Comparative patch analysis is a hybrid of comparative modeling based on a template complex and protein docking, with a greater applicability than comparative modeling and a higher accuracy than docking. It relies on structurally defined interactions of each of the complex components, or their homologs, with any other protein, irrespective of its fold. For each component, its known binding modes with other proteins of any fold are collected and expanded by the known binding modes of its homologs. These modes are then used to restrain conventional molecular docking, resulting in a set of binary domain complexes that are subsequently ranked by geometric complementarity and a statistical potential. The method is evaluated by predicting 20 binary complexes of known structure. It is able to correctly identify the binding mode in 70% of the benchmark complexes compared with 30% for protein docking. We applied comparative patch analysis to model the complex of the third PSD-95, DLG, and ZO-1 (PDZ) domain and the SH3-GK domains in the PSD-95 protein, whose structure is unknown. In the first predicted configuration of the domains, PDZ interacts with SH3, leaving both the GMP-binding site of guanylate kinase (GK) and the C-terminus binding cleft of PDZ accessible, while in the second configuration PDZ interacts with GK, burying both binding sites. We suggest that the two alternate configurations correspond to the different functional forms of PSD-95 and provide a possible structural description for the experimentally observed cooperative folding transitions in PSD-95 and its homologs. More generally, we expect that comparative patch analysis will provide useful spatial restraints for the structural characterization of an increasing number of binary and higher-order protein complexes.
authors.affiliation: Department of Biopharmaceutical Sciences, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Dmitry
authors.initials: D
authors.lastname: Korkin
authors.forename: Fred P
authors.initials: FP
authors.lastname: Davis
authors.forename: Frank
authors.initials: F
authors.lastname: Alber
authors.forename: Tinh
authors.initials: T
authors.lastname: Luong
authors.forename: Min-Yi
authors.initials: MY
authors.lastname: Shen
authors.forename: Vladan
authors.initials: V
authors.lastname: Lucic
authors.forename: Mary B
authors.initials: MB
authors.lastname: Kennedy
authors.forename: Andrej
authors.initials: A
authors.lastname: Sali
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003198:Computer Simulation; D019281:Dimerization; D000076122:Disks Large Homolog 4 Protein; D051528:Guanylate Kinases; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes / Q000737:chemistry / Q000648:ultrastructure; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping / Q000379:methods*; D020539:Sequence Analysis, Protein / Q000379:methods*
chemical_list: D000076122:Disks Large Homolog 4 Protein; C501447:Dlg4 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D046912:Multiprotein Complexes; D051528:Guanylate Kinases