title: Mutations in circularly permuted GTPase family genes AtNOA1/RIF1/SVR10 and BPG2 suppress var2-mediated leaf variegation in Arabidopsis thaliana.
abstract: Leaf variegation mutants constitute a unique group of chloroplast development mutants and are ideal genetic materials to dissect the regulation of chloroplast development. We have utilized the Arabidopsis yellow variegated (var2) mutant and genetic suppressor analysis to probe the mechanisms of chloroplast development. Here we report the isolation of a new var2 suppressor locus SUPPRESSOR OF VARIEGATION (SVR10). Genetic mapping and molecular complementation indicated that SVR10 encodes a circularly permuted GTPase that has been reported as Arabidopsis thaliana NITRIC OXIDE ASSOCIATED 1 (AtNOA1) and RESISTANT TO INHIBITION BY FOSMIDOMYCIN 1 (RIF1). Biochemical evidence showed that SVR10/AtNOA1/RIF1 likely localizes to the chloroplast stroma. We further demonstrate that the mutant of a close homologue of SVR10/AtNOA1/RIF1, BRASSINAZOLE INSENSITIVE PALE GREEN 2 (BPG2), can also suppress var2 leaf variegation. Mutants of SVR10 and BPG2 are impaired in photosynthesis and the accumulation of chloroplast proteins. Interestingly, two-dimensional blue native gel analysis showed that mutants of SVR10 and BPG2 display defects in the assembly of thylakoid membrane complexes including reduced levels of major photosynthetic complexes and the abnormal accumulation of a chlorophyll-protein supercomplex containing photosystem I. Taken together, our findings suggest that SVR10 and BPG2 are functionally related with VAR2, likely through their potential roles in regulating chloroplast protein homeostasis, and both SVR10 and BPG2 are required for efficient thylakoid protein complex assembly and photosynthesis.
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Yafei
authors.initials: Y
authors.lastname: Qi
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Rui
authors.initials: R
authors.lastname: An
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Juan
authors.initials: J
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Shuang
authors.initials: S
authors.lastname: Liang
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Jingxia
authors.initials: J
authors.lastname: Shao
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Xiayan
authors.initials: X
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China.
authors.forename: Lijun
authors.initials: L
authors.lastname: An
authors.affiliation: State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, 712100, Shaanxi, People's Republic of China. flyfeiyu@gmail.com.
authors.forename: Fei
authors.initials: F
authors.lastname: Yu
mesh_terms: D049069:ATP-Dependent Proteases / Q000378:metabolism*; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D003001:Cloning, Molecular; D005453:Fluorescence; D020558:GTP Phosphohydrolases / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D005816:Genetic Complementation Test; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D019001:Nitric Oxide Synthase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D010802:Phylogeny; D018515:Plant Leaves / Q000502:physiology*; D020524:Thylakoids / Q000378:metabolism
chemical_list: D049069:ATP-Dependent Proteases; D029681:Arabidopsis Proteins; D002734:Chlorophyll; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D008565:Membrane Proteins; D019001:Nitric Oxide Synthase; C521947:NOA1 protein, Arabidopsis; C402651:AT2G30950 protein, Arabidopsis; C551728:BPG2 protein, Arabidopsis
keywords: Chloroplast development; Genetic suppressor; Leaf variegation; SVR10/AtNOA1/RIF1; VAR2