Abstract
VAR1 and VAR2 are the ATP-dependent metalloproteases homologous to bacterial FtsH and located in thylakoid membranes in Arabidopsis. Loss of either protein in the mutant alleles leads to leaf variegation. In general, leaf variegation is more severe in var2 than in var1. Mutant leaves of both mutants show a dramatic decrease of PSII activity under exposure to high light, suggesting that both proteases are involved in the repair cycle of photodamaged PSII. We have shown that VAR1 and VAR2 form a protein complex, and that the accumulation of the two proteins is mutually affected in the var mutants. In order to understand the correlation between VAR1/VAR2 protein levels and leaf-variegated phenotypes, all the var2 alleles (var2-7 to var2-21), isolated from our previous complementation analysis, were further characterized in this study. We determined mutations in each allele and compared their effects on the accumulation level of VAR1 and VAR2.
