Regulation of light capture
ATP-dependent zinc metalloprotease (FtsH) 4 and FtsH 2, both involved in “PSII associated light-harvesting complex II (LHCII) catabolic process”, were significantly upregulated (Fig. 2A). Three proteins responsible for antenna assembly, including LHCII protein Lhcb3, low PSII accumulation 3 (LPA3) assisting chlorophyll a binding protein CP43 assembly within PSII, and PsaH binding light-harvesting complex I protein Lhca2 to PSI core complex (Table S1), were downregulated, suggesting a decrease of antenna size following light exposure. The distinct interactions of PsbO with Lhcb3, PsaH were shown in the PPI network, indicating the potential of OEC to regulate antenna assembly (Fig. 2B).
Regulation of electron transport
Proteome data revealed that the proteins involved in PSII assembly, such as high chlorophyll fluorescence phenotype244 (HCF244), domain of unknown function (DUF1995) and thylakoid formation 1 (THF1), displayed upregulation expression, indicating that continuous repair was required to retain PSII functionality. The proteins involved in electron donating to PSI reaction center P700+, such as proton gradient regulation 5 (PGR5) and PsaN, were also upregulated, indicating the activation of the PGR5-dependent PSI-CEF (Fig. 2A). In addition, the protein called acclimation of photosynthesis to environment was upregulated, contributing to the acclimation of photosynthetic electron transfer to illumination (Table S1). The interactions between PsbO and HCF244, as well as PGR5 and PsaN, shown in the PPI network, suggested the need of electron transport regulation due to the partially impaired OEC (Fig. 2B).