Endoplasmic Reticulum Export Sites and Golgi Bodies Behave as Single Mobile Secretory Units in Plant Cells[W]
Author:
daSilva Luis L.P.1, Snapp Erik L.2, Denecke Jürgen1, Lippincott-Schwartz Jennifer2, Hawes Chris3, Brandizzi Federica3
Affiliation:
1. Centre of Plant Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom 2. Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892 3. Research School of Biological and Molecular Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom
Abstract
AbstractIn contrast with animals, plant cells contain multiple mobile Golgi stacks distributed over the entire cytoplasm. However, the distribution and dynamics of protein export sites on the plant endoplasmic reticulum (ER) surface have yet to be characterized. A widely accepted model for ER-to-Golgi transport is based on the sequential action of COPII and COPI coat complexes. The COPII complex assembles by the ordered recruitment of cytosolic components on the ER membrane. Here, we have visualized two early components of the COPII machinery, the small GTPase Sar1p and its GTP exchanging factor Sec12p in live tobacco (Nicotiana tabacum) leaf epidermal cells. By in vivo confocal laser scanning microscopy and fluorescence recovery after photobleaching experiments, we show that Sar1p cycles on mobile punctate structures that track with the Golgi bodies in close proximity but contain regions that are physically separated from the Golgi bodies. By contrast, Sec12p is uniformly distributed along the ER network and does not accumulate in these structures, consistent with the fact that Sec12p does not become part of a COPII vesicle. We propose that punctate accumulation of Sar1p represents ER export sites (ERES). The sites may represent a combination of Sar1p-coated ER membranes, nascent COPII membranes, and COPII vectors in transit, which have yet to lose their coats. ERES can be induced by overproducing Golgi membrane proteins but not soluble bulk-flow cargos. Few punctate Sar1p loci were observed that are independent of Golgi bodies, and these may be nascent ERES. The vast majority of ERES form secretory units that move along the surface of the ER together with the Golgi bodies, but movement does not influence the rate of cargo transport between these two organelles. Moreover, we could demonstrate using the drug brefeldin A that formation of ERES is strictly dependent on a functional retrograde transport route from the Golgi apparatus.
Publisher
Oxford University Press (OUP)
Subject
Cell Biology,Plant Science
Reference68 articles.
1. Allan, B.B., Moyer, B.D., and Balch, W.E. (2000). Rab1 recruitment of p115 into a cis-SNARE complex: Programming budding COPII vesicles for fusion. Science 289 , 444–448. 2. Andreeva, A.V., Zheng, H., Saint-Jore, C.M., Kutuzov, M.A., Evans, D.E., and Hawes, C.R. (2000). Organization of transport from endoplasmic reticulum to Golgi in higher plants. Biochem. Soc. Trans. 28 , 505–512. 3. Antonny, B., Gounon, P., Schekman, R., and Orci, L. (2003). Self-assembly of minimal COPII cages. EMBO Rep. 4 , 419–424. 4. Antonny, B., Madden, D., Hamamoto, S., Orci, L., and Schekman, R. (2001). Dynamics of the COPII coat with GTP and stable analogues. Nat. Cell Biol. 3 , 531–537. 5. Aridor, M., Bannykh, S.I., Rowe, T., and Balch, W.E. (1995). Sequential coupling between COPII and COPI vesicle coats in endoplasmic reticulum to Golgi transport. J. Cell Biol. 131 , 875–893.
Cited by
255 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|