Shanghai Researchers Reveal a Concerted Biogenesis Mechanism for Three Photosynthetic Complexes in Higher Plants
On May 10, 2016 (Beijing time), the partnership journal of nature publishing group, Cell Discovery online published a research paper entitled “PBR1 selectively controls biogenesis of photosynthetic complexes by modulating translation of the large chloroplast gene Ycf1 in Arabidopsis”, from Prof. Guo Fang-Qing’s group of Institute of Plant Physiology and Ecology (SIPPE), Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences. In this study, authors reveal the importance of the PBR1-Ycf1 module for translational control of the concerted biogenesis of Photosystem I (PSI), cytochrome b6f (Cyt b6f ) and NADH dehydrogenase (NDH) complexes as these three complexes have long been known to play a platform role in cyclic electron transfer around PSI during photosynthesis. Prior to this study, it is not known whether and how the biogenesis processes of these three complexes are finely coordinated.
Given that the photosynthetic complexes photosystem I (PSI), cytochrome b6f (Cytb6f ) and NADH dehydrogenase (NDH) each consist of both plastid- and nucleus-encoded subunits, the concerted accumulation of the various subunits of photosynthetic complexes in chloroplasts relies on a tight cooperation between the plastid and nucleus genomes. Here, authors report the identification of PHOTOSYSTEM BIOGENESIS REGULATOR 1 (PBR1), a nuclear-encoded chloroplast RNA-binding protein that regulates the concerted biogenesis of NDH, PSI and Cytb6f complexes. They identified Ycf1, one of the two largest chloroplast genome-encoded open reading frames, as the direct downstream target protein of PBR1 by measuring the rate of translation of the chloroplast-encoded polypeptides as determined by pulse labeling experiments with both genetic loss-of-function and gain-of-function studies. Biochemical and molecular analyses reveal that PBR1 regulates the translation of Ycf1 by directly binding to its mRNA. Importantly, these findings demonstrate that the PBR1-Ycf1 module not only acts as a common fate determinant regulating biogenesis of NDH, PSI and Cytb6f complexes but also perhaps functions as part of a developmental timer due to the strong light-inducible expressions of PBR1 during chloroplast development.
This work was supported by grants from the Ministry of Science and Technology of China (2012CB944802) and the National Natural Science Foundation of China (91317305 and 31570260) and the Chinese Academy of Sciences.
Fang-Qing Guo (correspondence author) Ph. D, Professor
The National Key Laboratory of Plant Molecular Genetics,
Institute of Plant Physiology & Ecology,
Shanghai Institutes for Biological Sciences,
Chinese Academy of Sciences,
300 Fenglin Road, Shanghai 200032, CHINA
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