Abstract
We have shown that the VAR1 and VAR2 loci in Arabidopsis encode an FtsH metalloprotease located in thylakoid membranes of chloroplasts, and that a mutation at either one gene causes leaf variegation. VAR1 and VAR2 are suggested to coordinately participate in protein degradation pathway of photosynthetic protein complexes in thylakoid membranes, and play an important role in photoprotection. FtsH comprises a gene family in Arabidopsis and 12 genes including VAR1 and VAR2 can be found. We performed a transient expression assay in suspension-cultured tobacco cells using a GFP gene fused to a putative targeting signal, and showed that 9 FtsHs are localized in chloroplasts and 3 FtsHs are localized in mitochondria. To investigate the function of these genes, an attempt to isolate T-DNA insertion mutants is underway.
