Light-independent biosynthesis and assembly of the photosystem II complex in the diatom Chaetoceros gracilis.

Diatoms can survive for long periods in the dark. However, how biosynthesis of photosynthetic proteins contributes to survival in the dark is poorly understood. Using a radiolabeling technique, we examined whether de novo biosynthesis and assembly of photosynthetic proteins differs in light-adapted vs. dark-adapted marine diatoms (Chaetoceros gracilis). In light-adapted cells, D1 protein was heavily radiolabeled owing to rapid turnover of photosystem II (PSII). In dark-adapted cells (>24 h), the radiolabeling patterns of PSII components changed, but the PSII dimer still formed. Therefore, diatoms may regulate the biosynthesis of photosynthetic proteins for long-term survival in the dark.