Required to maintain light harvesting efficiency, especially during nonphotochemical quenching (NPQ) recovery, via the regulation of chlorophyll excited-state lifetime probably by preventing the formation of a slowly reversible form of antenna quenching. Mostly localized in thylakoid grana margins, and, to a lower extent, in grana and stroma lamellae. High light intensity-dependent and irreversible nonphotochemical quenching (NPQ) due to a decrease in chlorophyll excited-state lifetime. In the N-terminal section; belongs to the HAD-like hydrolase superfamily. In the C-terminal section; belongs to the thioredoxin family.