title: PBR1 selectively controls biogenesis of photosynthetic complexes by modulating translation of the large chloroplast gene Ycf1 in Arabidopsis.
abstract: The biogenesis of photosystem I (PSI), cytochrome b 6 f (Cytb 6 f) and NADH dehydrogenase (NDH) complexes relies on the spatially and temporally coordinated expression and translation of both nuclear and chloroplast genes. Here we 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 Cytb 6 f complexes. We identified Ycf1, one of the two largest chloroplast genome-encoded open reading frames as the direct downstream target protein of PBR1. Biochemical and molecular analyses reveal that PBR1 regulates Ycf1 translation by directly binding to its mRNA. Surprisingly, we further demonstrate that relocation of the chloroplast gene Ycf1 fused with a plastid-transit sequence to the nucleus bypasses the requirement of PBR1 for Ycf1 translation, which sufficiently complements the defects in biogenesis of NDH, PSI and Cytb 6 f complexes in PBR1-deficient plants. Remarkably, the nuclear-encoded PBR1 tightly controls the expression of the chloroplast gene Ycf1 at the translational level, which is sufficient to sustain the coordinated biogenesis of NDH, PSI and Cytb 6 f complexes as a whole. Our findings provide deep insights into better understanding of how a predominant nuclear-encoded factor can act as a migratory mediator and undergoes selective translational regulation of the target plastid gene in controlling biogenesis of photosynthetic complexes.
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China.
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Yang
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Wang
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China.
authors.forename: Si-Ting
authors.initials: ST
authors.lastname: Chen
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China.
authors.forename: Ji-Kai
authors.initials: JK
authors.lastname: Li
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences , Shanghai, China.
authors.forename: Hong-Tao
authors.initials: HT
authors.lastname: Shen
authors.affiliation: The National Key Laboratory of Plant Molecular Genetics, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; National Center of Plant Gene Research (Shanghai), Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China; CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China.
authors.forename: Fang-Qing
authors.initials: FQ
authors.lastname: Guo
keywords: RNA-binding protein; Ycf1; biogenesis; photosynthetic complex