Plant Physiol. Tips for Better Browsing
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
QUICK SEARCH:   [advanced]


     

Plant Physiology Preview
Published on February 20, 2008; 10.1104/pp.107.115170

This Article
Right arrow Full Text (Plant Physiology Preview (PDF))
Right arrow Supplemental Data
Right arrow All Versions of this Article:
146/4/1571    most recent
pp.107.115170v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Kirchhoff, H.
Right arrow Articles by Mullineaux, C. W.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Kirchhoff, H.
Right arrow Articles by Mullineaux, C. W.
Agricola
Right arrow Articles by Kirchhoff, H.
Right arrow Articles by Mullineaux, C. W.

Received December 18, 2007
Accepted February 12, 2008

Protein diffusion and macromolecular crowding in thylakoid membranes

Helmut Kirchhoff , Silvia Haferkamp , John F. Allen , David Epstein , and Conrad W. Mullineaux *

Institute of Botany, Schlossgarten 3, 48149 Munster, Germany; School of Biological and Chemical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS, United Kingdom; Mathematics Institute, University of Warwick, Coventry CV4 7AL, UK

* Corresponding author; email: c.mullineaux{at}qmul.ac.uk.

The photosynthetic light-reactions of green plants are mediated by chlorophyll-binding protein complexes located in the thylakoid membranes within the chloroplasts. Thylakoid membranes have a complex structure, with lateral segregation of protein complexes into distinct membrane regions known as the grana and the stroma lamellae. It has long been clear that some protein complexes can diffuse between the grana and the stroma lamellae, and that this movement is important for processes including membrane biogenesis, regulation of light-harvesting and turnover and repair of the photosynthetic complexes. In the grana membranes, diffusion may be problematic since the protein complexes are very densely packed (approximately 75 % area occupation) and semi-crystalline protein arrays are often observed. To date, direct measurements of protein diffusion in green plant thylakoids have been lacking. We have developed a form of Fluorescence Recovery after Photobleaching that allows direct measurement of the diffusion of chlorophyll-protein complexes in isolated grana membranes from spinach. We show that about 75% of fluorophores are immobile within our measuring period of a few minutes. We suggest that this immobility is due to a protein network covering a whole grana disc. However, the remaining fraction is surprisingly mobile (diffusion coefficient 4.6 ± 0.4 x 10-11 cm2 s-1), which suggests that it is associated with mobile proteins which exchange between the grana and stroma lamellae within a few seconds. Manipulation of the protein:lipid ratio and the ionic strength of the buffer reveals the roles of macromolecular crowding and protein-protein interactions in restricting the mobility of grana proteins.






HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH
ASPB Publications PLANT PHYSIOLOGY THE PLANT CELL
Copyright © 2008 by the American Society of Plant Biologists