The structural basis of Arf effector specificity: the crystal structure of ARF6 in a complex with JIP4.
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Isabet T, Montagnac G, Regazzoni K, Raynal B, El Khadali F, England P, Franco M, Chavrier P, Houdusse A, Menetrey J
The structural basis of Arf effector specificity: the crystal structure of ARF6 in a complex with JIP4.
EMBO J. 2009 Sep 16;28(18):2835-45. doi: 10.1038/emboj.2009.209. Epub 2009 Jul 30.
- PubMed ID
- 19644450 [ View in PubMed]
- Abstract
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.