title: A Steric-inhibition model for regulation of nucleotide exchange via the Dock180 family of GEFs.
abstract: CDM (CED-5, Dock180, Myoblast city) family members have been recently identified as novel, evolutionarily conserved guanine nucleotide exchange factors (GEFs) for Rho-family GTPases . They regulate multiple processes, including embryonic development, cell migration, apoptotic-cell engulfment, tumor invasion, and HIV-1 infection, in diverse model systems . However, the mechanism(s) of regulation of CDM proteins has not been well understood. Here, our studies on the prototype member Dock180 reveal a steric-inhibition model for regulating the Dock180 family of GEFs. At basal state, the N-terminal SH3 domain of Dock180 binds to the distant catalytic Docker domain and negatively regulates the function of Dock180. Further studies revealed that the SH3:Docker interaction sterically blocks Rac access to the Docker domain. Interestingly, ELMO binding to the SH3 domain of Dock180 disrupted the SH3:Docker interaction, facilitated Rac access to the Docker domain, and contributed to the GEF activity of the Dock180/ELMO complex. Additional genetic rescue studies in C. elegans suggested that the regulation of the Docker-domain-mediated GEF activity by the SH3 domain and its adjoining region is evolutionarily conserved. This steric-inhibition model may be a general mechanism for regulating multiple SH3-domain-containing Dock180 family members and may have implications for a variety of biological processes.
authors.affiliation: Beirne Carter Center for Immunology Research, Department of Microbiology, University of Virginia, Charlottesville, VA 22908 USA.
authors.forename: Mingjian
authors.initials: M
authors.lastname: Lu
authors.forename: Jason M
authors.initials: JM
authors.lastname: Kinchen
authors.forename: Kent L
authors.initials: KL
authors.lastname: Rossman
authors.forename: Cynthia
authors.initials: C
authors.lastname: Grimsley
authors.forename: Matthew
authors.initials: M
authors.lastname: Hall
authors.forename: John
authors.initials: J
authors.lastname: Sondek
authors.forename: Michael O
authors.initials: MO
authors.lastname: Hengartner
authors.forename: Vijay
authors.initials: V
authors.lastname: Yajnik
authors.forename: Kodi S
authors.initials: KS
authors.lastname: Ravichandran
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D017173:Caenorhabditis elegans; D002478:Cells, Cultured; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D008954:Models, Biological; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D020744:rac GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020741:rho GTP-Binding Proteins / Q000378:metabolism*; D018909:src Homology Domains / Q000235:genetics*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C099818:DOCK1 protein, human; C465214:ELMO1 protein, human; D020662:Guanine Nucleotide Exchange Factors; D020744:rac GTP-Binding Proteins; D020741:rho GTP-Binding Proteins