Positive-strand RNA viruses invariably assemble their viral replication complexes (VRCs) by remodeling host intracellular membranes. How viral replication proteins are targeted to specific organelle membranes to initiate VRC assembly remains elusive. Brome mosaic virus (BMV), whose replication can be recapitulated in Saccharomyces cerevisiae, assembles its VRCs by invaginating the outer perinuclear endoplasmic reticulum (ER) membrane. Remarkably, BMV replication protein 1a (BMV 1a) is the only viral protein required for such membrane remodeling. We show that ER-vesicle protein of 14 kD (Erv14), a cargo receptor of coat protein complex II (COPII), interacts with BMV 1a. Moreover, the perinuclear ER localization of BMV 1a is disrupted in cells lacking ERV14 or expressing dysfunctional COPII coat components (Sec13, Sec24 or Sec31). The requirement of Erv14 for the localization of BMV 1a is bypassed by addition of a Sec24-recognizable sorting signal to BMV 1a or by overexpressing Sec24, suggesting a coordinated effort by both Erv14 and Sec24 for the proper localization of BMV 1a. The COPII pathway is well known for being involved in protein secretion; our data suggest that a subset of COPII coat proteins have an unrecognized role in targeting proteins to the perinuclear ER membrane.
The authors declare no competing or financial interests.
X.W., J.L. and M.S. conceived and designed the experiments; J.L., S.F. and J.Z. performed the experiments; J.L. and S.F. analyzed data; X.W., J.L. and M.S. wrote the manuscript; and X.W. coordinated the study.
This work was supported by an US-Israel Binational Science Foundation (BSF) collaborative grant [grant number 2013101 to Elizabeth Miller (MRC Laboratory of Molecular Biology, Cambridge, UK) and M.S.]; and a Virginia Tech Startup and a National Science Foundation (NSF) grant [grant number 1265260 to X.W.].
Supplementary information available online at http://jcs.biologists.org/lookup/doi/10.1242/jcs.190082.supplemental
- Received March 30, 2016.
- Accepted August 13, 2016.
- © 2016. Published by The Company of Biologists Ltd