CBSX2 is required for the efficient oxidation of chloroplast redox-regulated enzymes in darkness.

Thiol/disulfide-based redox regulation in plant chloroplasts is essential for controlling the activity of target proteins in response to light signals. One of the examples of such a role in chloroplasts is the activity of the chloroplast ATP synthase (CFCF), which is regulated by the redox state of the CFγ subunit and involves two cysteines in its central domain. To investigate the mechanism underlying the oxidation of CFγ and other chloroplast redox-regulated enzymes in the dark, we characterized the Arabidopsis mutant, which was isolated based on its altered NPQ (non-photochemical quenching) induction upon illumination.