Poster: Photosynthesis

Abs # 375: Functional diversity of the Arabidopsis FtsH gene family

Presenter:	Yu, Fei , feiyu@iastate.edu
Authors	Yu, Fei  (A)   Park, Sungsoon  (A)   Rodermel, Steven R. (A)
Affiliations:	(A): Iowa State University

FtsH is a membrane-bound metalloprotease involved in the degradation of a number of substrates in E. coli. It belongs to the AAA (ATPase associated with various cellular activities) protein family and contains a single ATP binding domain. In Arabidopsis, FtsH genes form a small family with at least twelve members. Among these, AtFtsH1 participates in the degradation of the Photosystem II D1 protein 23kD fragment during the D1 protein turnover process. By positional cloning of an Arabidopsis variegation mutant, var2, which contains both green and white leave sectors, our lab identified another FtsH homologue--AtFtsH2 (VAR2). Recently, another Arabidopsis variegation mutant gene, var1, was cloned and VAR1 was shown to be identical to AtFtsH5. Both AtFtsH2 and AtFtsH5 are located in chloroplasts and it has been shown that chloroplast photoprotection is impaired in both var2 and var1. In the present study, complementation experiments were carried out and it was determined that some Arabidopsis FtsH homologues share redundant functions. We also determined that in mutants with altered FtsH activities, chloroplast FtsH protein equilibrium is disrupted, suggesting that there are interactions among these proteins. Detailed mutant analysis is underway to better understand the functional relationships between the various FtsH homologues and the mechanisms of leaf variegation.