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A critical role for the Var2 FtsH homologue of Arabidopsis thaliana in the photosystem II repair cycle in vivo

A critical role for the Var2 FtsH homologue of Arabidopsis thaliana in the photosystem II repair cycle in vivo

Bailey, Shaun, Thompson, Elinor ORCID: 0000-0002-6434-9290, Nixon, Peter J., Horton, Peter, Mullineaux, Conrad W., Robinson, Colin and Mann, Nicholas H. (2001) A critical role for the Var2 FtsH homologue of Arabidopsis thaliana in the photosystem II repair cycle in vivo. The Journal of Biological Chemistry, 277 (3). pp. 2006-2011. ISSN 0021-9258 (Print), 1083-351X (Online) (doi:https://doi.org/10.1074/jbc.M105878200)

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Abstract

Using a var2-2 mutant of Arabidopsis 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.

Item Type: Article
Uncontrolled Keywords: FtsH, Photosystem II, protease
Faculty / School / Research Centre / Research Group: Faculty of Education, Health & Human Sciences > School of Human Sciences (HUM)
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Last Modified: 09 Oct 2021 04:46
URI: http://gala.gre.ac.uk/id/eprint/4224

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