title: Cell growth defect factor1/chaperone-like protein of POR1 plays a role in stabilization of light-dependent protochlorophyllide oxidoreductase in Nicotiana benthamiana and Arabidopsis.
abstract: Angiosperms require light for chlorophyll biosynthesis because one reaction in the pathway, the reduction of protochlorophyllide (Pchlide) to chlorophyllide, is catalyzed by the light-dependent protochlorophyllide oxidoreductase (POR). Here, we report that Cell growth defect factor1 (Cdf1), renamed here as chaperone-like protein of POR1 (CPP1), an essential protein for chloroplast development, plays a role in the regulation of POR stability and function. Cdf1/CPP1 contains a J-like domain and three transmembrane domains, is localized in the thylakoid and envelope membranes, and interacts with POR isoforms in chloroplasts. CPP1 can stabilize POR proteins with its holdase chaperone activity. CPP1 deficiency results in diminished POR protein accumulation and defective chlorophyll synthesis, leading to photobleaching and growth inhibition of plants under light conditions. CPP1 depletion also causes reduced POR accumulation in etioplasts of dark-grown plants and as a result impairs the formation of prolamellar bodies, which subsequently affects chloroplast biogenesis upon illumination. Furthermore, in cyanobacteria, the CPP1 homolog critically regulates POR accumulation and chlorophyll synthesis under high-light conditions, in which the dark-operative Pchlide oxidoreductase is repressed by its oxygen sensitivity. These findings and the ubiquitous presence of CPP1 in oxygenic photosynthetic organisms suggest the conserved nature of CPP1 function in the regulation of POR.
authors.affiliation: Department of Systems Biology, Yonsei University, Seoul 120-749, Korea.
authors.forename: Jae-Yong
authors.initials: JY
authors.lastname: Lee
authors.forename: Ho-Seok
authors.initials: HS
authors.lastname: Lee
authors.forename: Ji-Young
authors.initials: JY
authors.lastname: Song
authors.forename: Young Jun
authors.initials: YJ
authors.lastname: Jung
authors.forename: Steffen
authors.initials: S
authors.lastname: Reinbothe
authors.forename: Youn-Il
authors.initials: YI
authors.lastname: Park
authors.forename: Sang Yeol
authors.initials: SY
authors.lastname: Lee
authors.forename: Hyun-Sook
authors.initials: HS
authors.lastname: Pai
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000096:biosynthesis; D060365:Chloroplast Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D018832:Molecular Chaperones / Q000235:genetics / Q000378:metabolism*; D044925:Oxidoreductases Acting on CH-CH Group Donors / Q000235:genetics / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects; D011521:Protochlorophyllide / Q000378:metabolism; D034622:RNA Interference; D014026:Nicotiana / Q000201:enzymology / Q000235:genetics / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D018832:Molecular Chaperones; D002734:Chlorophyll; D011521:Protochlorophyllide; D044925:Oxidoreductases Acting on CH-CH Group Donors; C023886:protochlorophyllide reductase