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Published August 23, 2010 | Supplemental Material + Published
Journal Article Open

Lipid activation of the signal recognition particle receptor provides spatial coordination of protein targeting


The signal recognition particle (SRP) and SRP receptor comprise the major cellular machinery that mediates the cotranslational targeting of proteins to cellular membranes. It remains unclear how the delivery of cargos to the target membrane is spatially coordinated. We show here that phospholipid binding drives important conformational rearrangements that activate the bacterial SRP receptor FtsY and the SRP–FtsY complex. This leads to accelerated SRP–FtsY complex assembly, and allows the SRP–FtsY complex to more efficiently unload cargo proteins. Likewise, formation of an active SRP–FtsY GTPase complex exposes FtsY's lipid-binding helix and enables stable membrane association of the targeting complex. Thus, membrane binding, complex assembly with SRP, and cargo unloading are inextricably linked to each other via conformational changes in FtsY. These allosteric communications allow the membrane delivery of cargo proteins to be efficiently coupled to their subsequent unloading and translocation, thus providing spatial coordination during protein targeting.

Additional Information

© 2010 Lam et al. This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 3.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/3.0/). Submitted: 26 April 2010. Accepted: 26 July 2010. We thank Oded Lewinson in the Rees group for help and advice on liposome experiments, Jost Vielmetter at the Protein Expression Center (PEC) at Caltech and J. Van Deventer of the Tirrel group for help in SPR experiments, and Ray Deshaies and members of the Shan laboratory for comments on the manuscript. This work was supported by National Institutes of Health (NIH) grant GM078024, and career awards from the Burroughs Welcome Foundation, the Henry and Camille Dreyfus foundation, the Arnold and Mabel Beckman foundation, and the David and Lucile Packard foundation to S. Shan. D. Akopian and M. Rome were supported by NIH/National Research Service Award training grant 5T32GM07616. The Biacore instrument at the PEC is funded by the Moore Foundation grant for "Center for Integrative Study of Cell Regulation" and in part by Caltech's Beckman Institute Funds.

Attached Files

Published - Lam2010p11400J_Cell_Biol.pdf

Supplemental Material - JCB_201004129_sm.pdf


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