The structural basis of Arf effector specificity: the crystal structure of ARF6 in a complex with JIP4.

The JNK-interacting proteins, JIP3 and JIP4, are specific effectors of the small GTP-binding protein ARF6. The interaction of ARF6-GTP with the second leucine zipper (LZII) domains of JIP3/JIP4 regulates the binding of JIPs to kinesin-1 and dynactin. Here, we report the crystal structure of ARF6-GTP bound to the JIP4-LZII at ...
1.9 A resolution. The complex is a heterotetramer with dyad symmetry arranged in an ARF6-(JIP4)(2)-ARF6 configuration. Comparison of the ARF6-JIP4 interface with the equivalent region of ARF1 shows the structural basis of JIP4's specificity for ARF6. Using site-directed mutagenesis and surface plasmon resonance, we further show that non-conserved residues at the switch region borders are the key structural determinants of JIP4 specificity. A structure-derived model of the association of the ARF6-JIP3/JIP4 complex with membranes shows that the JIP4-LZII coiled-coil should lie along the membrane to prevent steric hindrances, resulting in only one ARF6 molecule bound. Such a heterotrimeric complex gives insights to better understand the ARF6-mediated motor switch regulatory function.
Mesh Terms:
ADP-Ribosylation Factors, Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Dimerization, Dynactin Complex, Guanosine Triphosphate, Kinesin, Microtubule-Associated Proteins, Models, Biological, Molecular Conformation, Molecular Sequence Data, Mutagenesis, Site-Directed, Protein Binding, Protein Conformation, Protein Structure, Secondary, Protein Structure, Tertiary, Surface Plasmon Resonance
EMBO J.
Date: Sep. 16, 2009
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