Figure 12.

Model for TEF30 function during PSII repair. When PSII is damaged (e.g. at HL intensities), the PSII complex enters the repair cycle. For this, PSII supercomplexes are disassembled and PSII monomers migrate from stacked into stroma-exposed membrane regions. After PSII monomers are partially disassembled to generate CP43-less forms, damaged D1 is degraded by FtsH and Deg proteases and a newly synthesized D1 copy is inserted into PSII monomers. At this step, TEF30 may facilitate incorporation of the new D1 protein and/or reassembly of CP43, bind to repaired PSII monomers to protect them from undergoing repeated repair cycles, or facilitate the migration of repaired PSII monomers back to stacked regions for supercomplex reassembly. These functions are not mutually exclusive.