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

This Article Full Text Full Text (PDF) Alert me when this article is cited 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 Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Spetea, C. Articles by Andersson, B. Search for Related Content PubMed PubMed Citation Articles by Spetea, C. Articles by Andersson, B. Social Bookmarking                      What's this?

J Biol Chem, Vol. 275, Issue 10, 7205-7211, March 10, 2000

GTP Enhances the Degradation of the Photosystem II D1 Protein Irrespective of Its Conformational Heterogeneity at the Q_B Site^*

Cornelia Spetea^§, Nir Keren^¶, Torill Hundal^§, Jean-Michel Doan, Itzhak Ohad^¶**, and Bertil Andersson^§

From the  Department of Biochemistry, Arrhenius Laboratories for Natural Sciences, Stockholm University, Stockholm SE-106 91, Sweden, the ^§ Division of Cell Biology, Linköping University, Linköping SE-581 85, Sweden, the ^¶ Department of Biological Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel, and  Department of Cell Biology, University Pierre and Marie Curie, Paris 75005, France

The light exposure history and/or binding of different herbicides at the Q_B site may induce heterogeneity of photosystem II acceptor side conformation that affects D1 protein degradation under photoinhibitory conditions. GTP was recently found to stimulate the D1 protein degradation of photoinactivated photosystem II (Spetea, C., Hundal, T., Lohmann, F., and Andersson, B. (1999) Proc. Natl. Acad. Sci. U. S. A. 96, 6547-6552). Here we report that GTP enhances the cleavage of the D1 protein D-E loop following exposure of thylakoid membranes to either high light, low light, or repetitive single turnover flashes but not to trypsin. GTP does not stimulate D1 protein degradation in the presence of herbicides known to affect the accessibility of the cleavage site to proteolysis. However, GTP stimulates degradation that can be induced even in darkness in some photosystem II conformers following binding of the PNO8 herbicide (Nakajima, Y., Yoshida, S., Inoue, Y., Yoneyama, K., and Ono, T. (1995) Biochim. Biophys. Acta 1230, 38-44). Both the PNO8- and the light-induced primary cleavage of the D1 protein occur in the grana membrane domains. The subsequent migration of photosytem II containing the D1 protein fragments to the stroma domains for secondary proteolysis is light-activated. We conclude that the GTP effect is not confined to a specific photoinactivation pathway nor to the conformational state of the photosytem II acceptor side. Consequently, GTP does not interact with the site of D1 protein cleavage but rather enhances the activity of the endogenous proteolytic system.

CiteULike

Complore

Connotea

Del.icio.us

Digg

Reddit

Technorati

This article has been cited by other articles:

				Y. Harel, I. Ohad, and A. Kaplan Activation of Photosynthesis and Resistance to Photoinhibition in Cyanobacteria within Biological Desert Crust Plant Physiology, October 1, 2004; 136(2): 3070 - 3079. [Abstract] [Full Text] [PDF]