Structures of the Sgt2/SGTA Dimerization Domain with the Get5/UBL4A UBL Domain Reveal an Interaction that Forms a Conserved Dynamic Interface
In the cytoplasm, the correct delivery of membrane proteins is an essential and highly regulated process. The posttranslational targeting of the important tail-anchor membrane (TA) proteins has recently been under intense investigation. A specialized pathway, called the guided entry of TA proteins (GET) pathway in yeast and the transmembrane domain recognition complex (TRC) pathway in vertebrates, recognizes endoplasmic-reticulum-targeted TA proteins and delivers them through a complex series of handoffs. An early step is the formation of a complex between Sgt2/SGTA, a cochaperone with a presumed ubiquitin-like-binding domain (UBD), and Get5/UBL4A, a ubiquitin-like domain (UBL)-containing protein. We structurally characterize this UBD/UBL interaction for both yeast and human proteins. This characterization is supported by biophysical studies that demonstrate that complex formation is mediated by electrostatics, generating an interface that has high-affinity with rapid kinetics. In total, this work provides a refined model of the interplay of Sgt2 homologs in TA targeting.
© 2012 The Authors. This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial-No Derivative Works License, which permits non-commercial use, distribution, and reproduction in any medium, provided the original author and source are credited. Received: July 20, 2012; Revised: September 25, 2012; Accepted: October 8, 2012; Published: November 8, 2012. We thank Yihong Ye (National Institutes of Health [NIH], Bethesda, MD) for valuable discussion and for providing unpublished data. We thank Shu-Ou Shan, Douglas Rees, Axel Müller, Meera Rao, Christian Suloway, and Michael Rome for critical readings of the manuscript. We thank members of the Clemons laboratory for support and useful discussions. We thank Graeme Card, Ana Gonzalez, and Michael Soltice for help with data collection at SSRL beamline 12-2; Robert Peterson and Juli Feigon for use of the 800 MHz NMR spectrometer at the University of California, Los Angeles; Jost Vielmetter, Harry Gristick, Claude Rogers, and Abigail Pulsipher for assistance with SPR and ITC experiments; and Gordon and Betty Moore for support at the Molecular Observatory at Caltech. Operations at the SSRL are supported by the U.S. Department of Energy and the NIH. W.M.C. is supported by NIH grant R01GM097572.
Published - 1-s2.0-S2211124712003464-main.pdf
Accepted Version - nihms-417446.pdf
Supplemental Material - mmc1.pdf
Supplemental Material - mmc2.pdf
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