Associate Professor The Chinese University of Hong Kong Hong Kong, Hong Kong
Body of Abstract: Chloroplast is the site of photosynthesis and the cytochrome b6f (Cyt b6f) complex is a multisubunit protein complex in chloroplast thylakoid membranes required for photosynthetic electron transport and energy conversion. However, the mechanisms of chloroplast development and Cyt b6f biogenesis have not be fully understood. Recently, we identified a nuclear-encoded chloroplast by characterinzing the new tiny albino 1 (nta1) mutant in Arabidopsis, which had severe defects in Cyt b6f accumulation and chloroplast development. NTA1 encodes an integral thylakoid membrane protein and contains a conserved DUF1279 domain. Overexpression of NTA1 could completely rescue the nta1 phenotypes, while knockout of NTA1 in wild type plants fully recapitulate the mutant phenotypes. Loss of NTA1 function severely impaired the accumulation of multiprotein complexes in thylakoid membranes, including photosystem I (PSI), PSII and Cyt b6f. Further, NTA1 was found to physically interact with four subunits of Cyt b6f through the DUF1279 domain and C-terminal sequence to mediate their assembly. In addition, transgenic study with truncated NTA1 indicated that a complete NTA1 protein is essential for its normal function in chloroplast and plant development. Taken together, our study identified NTA1 as a key regulator of chloroplast development and Cyt b6f complex assembly. Further studies are needed to tackle the mechanisms of NTA1 in chloroplast development and Cyt b6f assembly. (
Funding: This work was supported by the General Research Fund [CUHK Codes 14121915 and 14104521] and Area of Excellence Grants [AoE/M-403/16 and AoE/M-05/12] from the Research Grants Council [RGC] of Hong Kong, a grant from the National Natural Science Foundation of China [NSFC]-RGC Joint Scheme [N_CUHK452/17], and direct grants from the Chinese University of Hong Kong [CUHK]).