Structural basis of membrane targeting by the Dock180 family of Rho family guanine exchange factors (Rho-GEFs).
The Dock180 family of atypical Rho family guanine nucleotide exchange factors (Rho-GEFs) regulate a variety of processes involving cellular or subcellular polarization, including cell migration and phagocytosis. Each contains a Dock homology region-1 (DHR-1) domain that is required to localize its GEF activity to a specific membrane compartment where levels of phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P(3)) are up-regulated by the local activity of PtdIns 3-kinase. Here we define the structural and energetic bases of phosphoinositide specificity by the DHR-1 domain of Dock1 (a GEF for Rac1), and show that DHR-1 utilizes a C2 domain scaffold and surface loops to create a basic pocket on its upper surface for recognition of the PtdIns(3,4,5)P(3) head group. The pocket has many of the characteristics of those observed in pleckstrin homology domains. We show that point mutations in the pocket that abolish phospholipid binding in vitro ablate the ability of Dock1 to induce cell polarization, and propose a model that brings together recent mechanistic and structural studies to rationalize the central role of DHR-1 in dynamic membrane targeting of the Rho-GEF activity of Dock180.
Premkumar
Lakshmanane
L
Infectious and Inflammatory Disease Center, Sanford-Burnham Medical Research Institute, La Jolla, California 92037, USA.
Bobkov
Andrey A
AA
Patel
Manishha
M
Jaroszewski
Lukasz
L
Bankston
Laurie A
LA
Stec
Boguslaw
B
Vuori
Kristiina
K
Côté
Jean-Francois
JF
Liddington
Robert C
RC
D000818:Animals; D001665:Binding Sites; D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004331:Drosophila melanogaster; D006801:Humans; D008958:Models, Molecular; D005810:Multigene Family / Q000502:physiology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship; D020744:rac GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D003598:Cytoskeletal Proteins; D029721:Drosophila Proteins; D019869:Phosphatidylinositol 3-Kinases; D018129:Phosphatidylinositol Phosphates; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins; C099818:DOCK1 protein, human; C107441:mbc protein, Drosophila; C060974:phosphatidylinositol 3,4,5-triphosphate