Arabidopsis BSD2 reveals a novel redox regulation of Rubisco physiology in vivo

Plants need light energy to drive photosynthesis, but excess energy leads to the production of harmful reactive oxygen species (ROS), resulting in oxidative inactivation of target enzymes, including the photosynthetic CO(2)-fixing enzyme, ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco). It has been demonstrated in vitro that oxidatively inactivated Rubisco can be reactivated by the addition of reducing agents. Busch et al. (in The Plant Journal, doi: 10.1111/tpj.14617, 2020) recently demonstrated that bundle-sheath defective 2 (BSD2), a stroma-targeted protein formerly known as a late-assembly chaperone for Rubisco biosynthesis, can be responsible for such reactivation in vivo. Here, we propose a working model of the novel redox regulation in Rubisco activity. Redox of Rubisco may be a new target for improving photosynthesis.