Journal of Biological Chemistry
Volume 277, Issue 3, 18 January 2002, Pages 2006-2011
Journal home page for Journal of Biological Chemistry

MEMBRANE TRANSPORT STRUCTURE FUNCTION AND BIOGENESIS
A Critical Role for the Var2 FtsH Homologue of Arabidopsis thaliana in the Photosystem II Repair Cycle in Vivo*

https://doi.org/10.1074/jbc.M105878200Get rights and content
Under a Creative Commons license
open access

Using a var2-2 mutant ofArabidopsis thaliana, which lacks a homologue of the zinc-metalloprotease, FtsH, we demonstrate that this protease is required for the efficient turnover of the D1 polypeptide of photosystem II and protection against photoinhibition in vivo. We show that var2-2 leaves are much more susceptible to light-induced photosystem II photoinhibition than wild-type leaves. Furthermore, the rate of photosystem II photoinhibition in untreated var2-2 leaves is equivalent to that of var2-2 and wild-type leaves, which have been treated with lincomycin, an inhibitor of the photosystem II repair cycle at the level of D1 synthesis. This is in contrast to untreated wild-type leaves, which show a much slower rate of photosystem II photoinhibition due to an efficient photosystem II repair cycle. The recovery of var2-2 leaves from photosystem II photoinhibition is also impaired relative to wild-type. Using Western blot analysis in the presence of lincomycin we show that the D1 polypeptide remains stable in leaves of the var2-2 mutant under photoinhibitory conditions that lead to D1 degradation in wild-type leaves and that the abundance of DegP2 is not affected by thevar2-2 mutation. We conclude, therefore, that the Var2 FtsH homologue is required for the cleavage of the D1 polypeptide in vivo. In addition, we identify a conserved lumenal domain in Var2 that is unique to FtsH homologues from oxygenic phototrophs.

Cited by (0)

Published, JBC Papers in Press, November 20, 2001, DOI 10.1074/jbc.M105878200

*

This work was supported by a grant from the Biotechnology and Biological Sciences and Research Council (to N. H. M.).The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.