Get5 Carboxyl-terminal Domain Is a Novel Dimerization Motif That Tethers an Extended Get4/Get5 Complex
Tail-anchored trans-membrane proteins are targeted to membranes post-translationally. The proteins Get4 and Get5 form an obligate complex that catalyzes the transfer of tail-anchored proteins destined to the endoplasmic reticulum from Sgt2 to the cytosolic targeting factor Get3. Get5 forms a homodimer mediated by its carboxyl domain. We show here that a conserved motif exists within the carboxyl domain. A high resolution crystal structure and solution NMR structures of this motif reveal a novel and stable helical dimerization domain. We additionally determined a solution NMR structure of a divergent fungal homolog, and comparison of these structures allows annotation of specific stabilizing interactions. Using solution x-ray scattering and the structures of all folded domains, we present a model of the full-length Get4/Get5 complex.
© 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Received for publication, December 12, 2011, and in revised form, January 3, 2012 Published, JBC Papers in Press, January 17, 2012. The Molecular Observatory at Caltech is supported by the Gordon and Betty Moore Foundation, the Beckman Institute, and the Sanofi-Aventis Bioengineering Research Program. Operations at SSRL are supported by the United States Department of Energy and the National Institutes of Health. Supported by National Institutes of Health Grant R01GM097572, the Searle Scholar program, and a Burroughs-Wellcome Fund career award for the biological sciences. We thank S. O. Shan, M. E. Rome, C. J. M. Suloway, and H. B. Gristick for critical reading of the manuscript; members of the laboratory for support and useful discussions; Julie Hoy for help in data collection on our home source; Graeme Card, Ana Gonzalez, and Michael Soltice for help with data collection at SSRL BL12-2; and Tsutomu Matsui and Hiro Tsuruta (1962–August 2011) for help with bioSAXS data collection and processing at SSRL BL4-2.
Published - Chartron2012p17730J_Biol_Chem.pdf
Supplemental Material - jbc.M111.333252-1.pdf