title: Phosphoproteomic analysis of Rhodopseudomonas palustris reveals the role of pyruvate phosphate dikinase phosphorylation in lipid production.
abstract: Rhodopseudomonas palustris  (R. palustris) is a purple nonsulfur anoxygenic phototrophic bacterium with metabolic versatility and is able to grow under photoheterotrophic and chemoheterotrophic states. It has uses in carbon management, carbon recycling, hydrogen generation, and lipid production; therefore, it has the potential for bioenergy production and biodegradation. This study is the first to identify the phosphoproteome of R. palustris including 100 phosphopeptides from 54 phosphoproteins and 74 phosphopeptides from 42 phosphoproteins in chemoheterotrophic and photoheterotrophic growth conditions, respectively. In the identified phosphoproteome, phosphorylation at the threonine residue, Thr487, of pyruvate phosphate dikinase (PPDK, RPA1051) was found to participate in the regulation of carbon metabolism. Here, we show that PPDK enzyme activity is higher in photoheterotrophic growth, with Thr487 phosphorylation as a possible mediator. Under the same photoheterotrophic conditions, R. palustris with overexpressed wild-type PPDK showed an enhanced accumulation of total lipids than those with mutant PPDK (T487V) form. This study reveals the role of the PPDK in the production of biodiesel material, lipid content, with threonyl-phosphorylation as one of the possible regulatory events during photoheterotrophic growth in R. palustris.
authors.affiliation: Institute of Molecular and Cellular Biology, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Chia-Wei
authors.initials: CW
authors.lastname: Hu
authors.forename: Miao-Hsia
authors.initials: MH
authors.lastname: Lin
authors.forename: Hsuan-Cheng
authors.initials: HC
authors.lastname: Huang
authors.forename: Wei-Chi
authors.initials: WC
authors.lastname: Ku
authors.forename: Tsun-Hsuan
authors.initials: TH
authors.lastname: Yi
authors.forename: Chia-Feng
authors.initials: CF
authors.lastname: Tsai
authors.forename: Yu-Ju
authors.initials: YJ
authors.lastname: Chen
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Sugiyama
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Ishihama
authors.forename: Hsueh-Fen
authors.initials: HF
authors.lastname: Juan
authors.forename: Shih-Hsiung
authors.initials: SH
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001483:Base Sequence; D002853:Chromatography, Liquid; D003001:Cloning, Molecular; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics; D008055:Lipids / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D020543:Proteome; D011772:Pyruvate, Orthophosphate Dikinase / Q000235:genetics / Q000378:metabolism*; D012241:Rhodopseudomonas / Q000201:enzymology / Q000378:metabolism*; D053719:Tandem Mass Spectrometry
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D008055:Lipids; D010750:Phosphoproteins; D020543:Proteome; D011772:Pyruvate, Orthophosphate Dikinase