title: Site-Specific Ser/Thr/Tyr Phosphoproteome of Sinorhizobium meliloti at Stationary Phase.
abstract: Sinorhizobium meliloti, a facultative microsymbiont of alfalfa, should fine-tune its cellular processes to live saprophytically in soils characterized with limited nutrients and diverse stresses. In this study, TiO2 enrichment and LC-MS/MS were used to uncover the site-specific Ser/Thr/Tyr phosphoproteome of S. meliloti in minimum medium at stationary phase. There are a total of 96 unique phosphorylated sites, with a Ser/Thr/Tyr distribution of 63:28:5, in 77 proteins. Phosphoproteins identified in S. meliloti showed a wide distribution pattern regarding to functional categories, such as replication, transcription, translation, posttranslational modification, transport and metabolism of amino acids, carbohydrate, inorganic ion, succinoglycan etc. Ser/Thr/Tyr phosphosites identified within the conserved motif in proteins of key cellular function indicate a crucial role of phosphorylation in modulating cellular physiology. Moreover, phosphorylation in proteins involved in processes related to rhizobial adaptation was also discussed, such as those identified in SMa0114 and PhaP2 (polyhydroxybutyrate synthesis), ActR (pH stress and microaerobic adaption), SupA (potassium stress), chaperonin GroEL2 (viability and potentially symbiosis), and ExoP (succinoglycan synthesis and secretion). These Ser/Thr/Tyr phosphosites identified herein would be helpful for our further investigation and understanding of the role of phosphorylation in rhizobial physiology.
authors.affiliation: State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China; Key Laboratory of Soil Microbiology, Ministry of Agriculture, China Agricultural University, Beijing, China; Rhizobium Research Center, China Agricultural University, Beijing, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China; Key Laboratory of Soil Microbiology, Ministry of Agriculture, China Agricultural University, Beijing, China; Rhizobium Research Center, China Agricultural University, Beijing, China.
authors.forename: Chang Fu
authors.initials: CF
authors.lastname: Tian
authors.affiliation: State Key Laboratory of Agrobiotechnology, and College of Biological Sciences, China Agricultural University, Beijing, China; Key Laboratory of Soil Microbiology, Ministry of Agriculture, China Agricultural University, Beijing, China; Rhizobium Research Center, China Agricultural University, Beijing, China.
authors.forename: Wen Xin
authors.initials: WX
authors.lastname: Chen
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D019295:Computational Biology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D020543:Proteome / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D012694:Serine / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism; D053719:Tandem Mass Spectrometry; D013912:Threonine / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D010750:Phosphoproteins; D020543:Proteome; D013912:Threonine; D014443:Tyrosine; D012694:Serine