title: Structural basis for mutual relief of the Rac guanine nucleotide exchange factor DOCK2 and its partner ELMO1 from their autoinhibited forms.
abstract: DOCK2, a hematopoietic cell-specific, atypical guanine nucleotide exchange factor, controls lymphocyte migration through ras-related C3 botulinum toxin substrate (Rac) activation. Dedicator of cytokinesis 2-engulfment and cell motility protein 1 (DOCK2•ELMO1) complex formation is required for DOCK2-mediated Rac signaling. In this study, we identified the N-terminal 177-residue fragment and the C-terminal 196-residue fragment of human DOCK2 and ELMO1, respectively, as the mutual binding regions, and solved the crystal structure of their complex at 2.1-Å resolution. The C-terminal Pro-rich tail of ELMO1 winds around the Src-homology 3 domain of DOCK2, and an intermolecular five-helix bundle is formed. Overall, the entire regions of both DOCK2 and ELMO1 assemble to create a rigid structure, which is required for the DOCK2•ELMO1 binding, as revealed by mutagenesis. Intriguingly, the DOCK2•ELMO1 interface hydrophobically buries a residue which, when mutated, reportedly relieves DOCK180 from autoinhibition. We demonstrated that the ELMO-interacting region and the DOCK-homology region 2 guanine nucleotide exchange factor domain of DOCK2 associate with each other for the autoinhibition, and that the assembly with ELMO1 weakens the interaction, relieving DOCK2 from the autoinhibition. The interactions between the N- and C-terminal regions of ELMO1 reportedly cause its autoinhibition, and binding with a DOCK protein relieves the autoinhibition for ras homolog gene family, member G binding and membrane localization. In fact, the DOCK2•ELMO1 interface also buries the ELMO1 residues required for the autoinhibition within the hydrophobic core of the helix bundle. Therefore, the present complex structure reveals the structural basis by which DOCK2 and ELMO1 mutually relieve their autoinhibition for the activation of Rac1 for lymphocyte chemotaxis.
authors.affiliation: RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro, Tsurumi, Yokohama 230-0045, Japan.
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hanawa-Suetsugu
authors.forename: Mutsuko
authors.initials: M
authors.lastname: Kukimoto-Niino
authors.forename: Chiemi
authors.initials: C
authors.lastname: Mishima-Tsumagari
authors.forename: Ryogo
authors.initials: R
authors.lastname: Akasaka
authors.forename: Noboru
authors.initials: N
authors.lastname: Ohsawa
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Sekine
authors.forename: Takuhiro
authors.initials: T
authors.lastname: Ito
authors.forename: Naoya
authors.initials: N
authors.lastname: Tochio
authors.forename: Seizo
authors.initials: S
authors.lastname: Koshiba
authors.forename: Takanori
authors.initials: T
authors.lastname: Kigawa
authors.forename: Takaho
authors.initials: T
authors.lastname: Terada
authors.forename: Mikako
authors.initials: M
authors.lastname: Shirouzu
authors.forename: Akihiko
authors.initials: A
authors.lastname: Nishikimi
authors.forename: Takehito
authors.initials: T
authors.lastname: Uruno
authors.forename: Tomoya
authors.initials: T
authors.lastname: Katakai
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kinashi
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kohda
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fukui
authors.forename: Shigeyuki
authors.initials: S
authors.lastname: Yokoyama
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020830:rac1 GTP-Binding Protein / Q000737:chemistry / Q000378:metabolism; D018909:src Homology Domains
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C402110:DOCK2 protein, human; C465214:ELMO1 protein, human; D020690:GTPase-Activating Proteins; D020662:Guanine Nucleotide Exchange Factors; C107953:RAC1 protein, human; D011993:Recombinant Fusion Proteins; D020830:rac1 GTP-Binding Protein