HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 282, Issue 2, 1170-1174, January 12, 2007

This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 282/2/1170    most recent M608124200v1 Submit a Letter to Editor Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Andersson, M. X. Articles by Sandelius, A. S. Search for Related Content PubMed PubMed Citation Articles by Andersson, M. X. Articles by Sandelius, A. S. Social Bookmarking                      What's this?

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts^*

Mats X. Andersson, Mattias Goksör, and Anna Stina Sandelius¹

From the Department of Plant and Environmental Sciences and the Department of Physics, Göteborg University, SE 405 30 Göteborg, Sweden

Eukaryote cells depend on membrane lipid trafficking from biogenic membranes, like the endoplasmic reticulum (ER), to other membranes in the cell. Two major routes for membrane lipid transport are recognized: vesicular trafficking and lipid transfer at zones of close contact between membranes. Specific ER regions involved in such membrane contact sites (MCSs) have been isolated, and lipid transfer at MCSs as well as protein-protein interactions between the partaking membranes have been demonstrated (reviewed by Holthuis, J. C. M., and Levine, T. P. (2005) Nat. Rev. 6, 209–220). Here we present the first demonstration of the physical association between membranes involved in MCSs: by using optical imaging and manipulation, strong attracting forces between ER and chloroplasts are revealed. We used Arabidopsis thaliana expressing green fluorescent protein in the ER lumen and observed leaf protoplasts by confocal microscopy. The ER network was evident, with ER branch end points apparently localized at chloroplast surfaces. After rupture of a protoplast using a laser scalpel, the cell content was released. ER fragments remained attached to the released chloroplasts and could be stretched out by optical tweezers. The applied force, 400 pN, could not drag a chloroplast free from its attached ER, which could reflect protein-protein interactions at the ER-chloroplast MCSs. As chloroplasts rely on import of ER-synthesized lipids, we propose that lipid transfer occurs at these MCSs. We suggest that lipid transfer at the MCSs also occurs in the opposite direction, for example to channel plastid-synthesized acyl groups to supply substrates for ER-localized synthesis of membrane and storage lipids.

Received for publication, August 23, 2006 , and in revised form, October 30, 2006.

^* This work was supported by The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning, the European Commission 6th framework program ATOM-3D (Contract No. 508952), the European Science Foundation EUROCORES program SPANAS, and C. F. Tryggers Stiftelse. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The on-line version of this article (available at http://www.jbc.org) contains supplemental movies 1–3.

¹ To whom correspondence should be addressed: Göteborg University, Dept. of Plant and Environmental Sciences, P. O. Box 461, SE 405 30 Göteborg, Sweden. Tel.: 46-317732611; Fax: 46-317732626; E-mail: annastina.sandelius{at}botany.gu.se.

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				C. Xu, J. Fan, A. J. Cornish, and C. Benning Lipid Trafficking between the Endoplasmic Reticulum and the Plastid in Arabidopsis Requires the Extraplastidic TGD4 Protein PLANT CELL, August 1, 2008; 20(8): 2190 - 2204. [Abstract] [Full Text] [PDF]

				E. Babiychuk, P. Bouvier-Nave, V. Compagnon, M. Suzuki, T. Muranaka, M. Van Montagu, S. Kushnir, and H. Schaller From the Cover: Allelic mutant series reveal distinct functions for Arabidopsis cycloartenol synthase 1 in cell viability and plastid biogenesis PNAS, February 26, 2008; 105(8): 3163 - 3168. [Abstract] [Full Text] [PDF]

				M. Fritz, H. Lokstein, D. Hackenberg, R. Welti, M. Roth, U. Zahringer, M. Fulda, W. Hellmeyer, C. Ott, F. P. Wolter, et al. Channeling of Eukaryotic Diacylglycerol into the Biosynthesis of Plastidial Phosphatidylglycerol J. Biol. Chem., February 16, 2007; 282(7): 4613 - 4625. [Abstract] [Full Text] [PDF]