The 30th International Conference on Arabidopsis Research (ICAR 2019)

479 / 2019-02-27 23:45:50

LOW PHOTOSYNTHETIC EFFICIENCY 1 is required for light-regulated photosystem II biogenesis in Arabidopsis

Chloroplast; photosynthesis; photosystem II biogenesis; D1 synthesis; light regulation.

Plenary track > Photosynthesis

Photosystem II (PSII), a multi-subunit protein complex of the photosynthetic electron transport chain, functions as a water-plastoquinone oxidoreductase which is vital to the initiation of photosynthesis and electron transport. Although the structure, composition, and function of PSII are well understood, the mechanism of PSII biogenesis remains largely elusive. Here, we identified a nuclear-encoded pentatricopeptide repeat (PPR) protein LOW PHOTOSYNTHETIC EFFICIENCY 1 (LPE1; encoded by At3g46610) in Arabidopsis, which plays a crucial role in PSII biogenesis. LPE1 is exclusively targeted to chloroplasts and directly binds to the 5' UTR of psbA mRNA which encodes PSII reaction center protein D1. The loss of LPE1 results in less efficient loading of ribosome on the psbA mRNA and great synthesis defects of D1 protein. We further found that LPE1 interacts with a known regulator of psbA mRNA translation HIGH CHLOROPHYLL FLUORESCENCE 173 (HCF173) and facilitates the association of HCF173 with psbA mRNA. More interestingly, our results indicate that LPE1 associates with psbA mRNA in a light-dependent manner through a redox-based mechanism. This study enhances our understanding of the mechanism of light-regulated D1 synthesis, which provides important insight into PSII biogenesis and functional maintenance of efficient photosynthesis in higher plants.