Effects of Changes of Redox Properties of the Chloroplast ATP Synthase in Arabidopsis

Abstract

Three mutations, designated as C199S, C205S, C199S/C205S, were generated by transformating wild type (Columbia ecotype) plants with the site-directed mutated gene constructs of gamma-subunit. The transgenes were overexpressed behind a constitutive 35S promoter compared with the endogenous gamma-subunit gene. In the isolated mutant chloroplasts, the high ATPase activities did not require DTT treatment while in the wild-type plant, ATPase activities increased after DTT treatment indicating that the cysteine to serine substitutions caused loss of the redox regulation and the ATP synthases were locked in reduced configuration. The "permanently reduced" ATP synthases could not be fully deactivated in the dark. There was no significant difference in photosynthesis rate and growth rate suggesting the redox regulation is not very important for plants.