title: Proline Coordination with Fatty Acid Synthesis and Redox Metabolism of Chloroplast and Mitochondria.
abstract: Proline (Pro) accumulation is one of the most prominent changes in plant metabolism during drought and low water potential; however, the regulation and function of Pro metabolism remain unclear. We used a combination of forward genetic screening based on a Proline Dehydrogenase1 (PDH1) promoter-luciferase reporter (PDH1pro:LUC2) and RNA sequencing of the Pro synthesis mutant p5cs1-4 to identify multiple loci affecting Pro accumulation in Arabidopsis (Arabidopsis thaliana). Two mutants having high PDH1pro:LUC2 expression and increased Pro accumulation at low water potential were found to be alleles of Cytochrome P450, Family 86, Subfamily A, Polypeptide2 (CYP86A2) and Long Chain Acyl Synthetase2 (LACS2), which catalyze two successive steps in very-long-chain fatty acid (VLCFA) synthesis. Reverse genetic experiments found additional VLCFA and lipid metabolism-related mutants with increased Pro accumulation. Altered cellular redox status is a key factor in the coordination of Pro and VLCFA metabolism. The NADPH oxidase inhibitor diphenyleneiodonium (DPI) induced high levels of Pro accumulation and strongly repressed PDH1pro:LUC2 expression. cyp86a2 and lacs2 mutants were hypersensitive to diphenyleneiodonium but could be reverted to wild-type Pro and PDH1pro:LUC2 expression by reactive oxygen species scavengers. The coordination of Pro and redox metabolism also was indicated by the altered expression of chloroplast and mitochondria electron transport genes in p5cs1-4 These results show that Pro metabolism is both influenced by and influences cellular redox status via previously unknown coordination with several metabolic pathways. In particular, Pro and VLCFA synthesis share dual roles to help buffer cellular redox status while producing products useful for stress resistance, namely the compatible solute Pro and cuticle lipids.
authors: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan.
authors: Suhas
authors: S
authors: Shinde
authors: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan.
authors: Joji Grace
authors: JG
authors: Villamor
authors: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan.
authors: Wendar
authors: W
authors: Lin
authors: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan.
authors: Sandeep
authors: 0000-0002-7462-5113
authors: S
authors: Sharma
authors: Institute of Plant and Microbial Biology, Academia Sinica, Taipei 115, Taiwan paulv@gate.sinica.edu.tw.
authors: Paul E
authors: PE
authors: Verslues
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism*; D003066:Coenzyme A Ligases / Q000235:genetics / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism; D005227:Fatty Acids / Q000096:biosynthesis*; D020869:Gene Expression Profiling / Q000379:methods; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism*; D009154:Mutation; D009861:Onium Compounds / Q000494:pharmacology; D010084:Oxidation-Reduction; D030821:Plants, Genetically Modified; D011392:Proline / Q000378:metabolism*; D011394:Proline Oxidase / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014867:Water / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; D005227:Fatty Acids; D009861:Onium Compounds; D014867:Water; C007517:diphenyleneiodonium; D003577:Cytochrome P-450 Enzyme System; D011392:Proline; D008156:Luciferases; C434730:CYP86A8 protein, Arabidopsis; C000595632:PDH1 protein, Arabidopsis; D011394:Proline Oxidase; D003066:Coenzyme A Ligases; C523086:LACS2 protein, Arabidopsis