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Site-Specific Ser/Thr/Tyr Phosphoproteome of Sinorhizobium meliloti at Stationary Phase.

Liu T, Tian CF, Chen WX - PLoS ONE (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.


Overview of the workflow and a representative MS/MS spectrum.MS/MS spectrum of the phosphopeptide L(pS)DGSGLDVIEAIR from the Ser-phosphorylated two-component response regulator ActR are shown, and the most abundant fragment ion corresponds to neutral loss of phosphoric acid (98 Da) from the phosphorylated Ser in the intact peptide.
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pone.0139143.g001: Overview of the workflow and a representative MS/MS spectrum.MS/MS spectrum of the phosphopeptide L(pS)DGSGLDVIEAIR from the Ser-phosphorylated two-component response regulator ActR are shown, and the most abundant fragment ion corresponds to neutral loss of phosphoric acid (98 Da) from the phosphorylated Ser in the intact peptide.

Mentions: S. meliloti CCBAU 01290 was found to be an effective microsymbiont, in terms of nitrogen-fixing efficiency and nodule occupation, for major alfalfa cultivars in north China [32, 33], and has been used as rhizobial inoculant in this region. Given the non- or slow-growing feature of rhizobia in natural soils characterized by limited nutrients and various stresses [44], stationary-phase bacterial cells in MM were used to determine the phosphoproteome of S. meliloti (Fig 1). Within detected 88 unique phosphopeptides, there are 68 phosphosites with high-confidence identification (localization probability above 0.75), 16 being medium-confidence (P value between 0.75 and 0.50), and 12 low-confidence sites (P value below 0.50). Details of these phosphopeptides are listed in S1 and S2 Tables, and a typical annotated spectrum is shown in Fig 1. Among the 96 unique phosphorylated sites in 77 proteins (S2 Table), the distribution of phosphoserine (pS), phosphothreonine (pT) and phosphotyrosine (pY) is 65.6%, 29.2% and 5.2%, respectively (S2 Table). The relative frequencies of these pS/pT/pY in S. meliloti are similar to L. monocytogenes, B. subtilis and E. coli etc. [23, 24, 27], but distinct from Campylobacter jejuni, Streptomyces coelicolor, Clostridium acetobutylicum, Latococcus lactis and C. synechococcus, which have more pT or a comparable number of pT than pS [28, 45–48].


Site-Specific Ser/Thr/Tyr Phosphoproteome of Sinorhizobium meliloti at Stationary Phase.

Liu T, Tian CF, Chen WX - PLoS ONE (2015)

Overview of the workflow and a representative MS/MS spectrum.MS/MS spectrum of the phosphopeptide L(pS)DGSGLDVIEAIR from the Ser-phosphorylated two-component response regulator ActR are shown, and the most abundant fragment ion corresponds to neutral loss of phosphoric acid (98 Da) from the phosphorylated Ser in the intact peptide.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4581636&req=5

pone.0139143.g001: Overview of the workflow and a representative MS/MS spectrum.MS/MS spectrum of the phosphopeptide L(pS)DGSGLDVIEAIR from the Ser-phosphorylated two-component response regulator ActR are shown, and the most abundant fragment ion corresponds to neutral loss of phosphoric acid (98 Da) from the phosphorylated Ser in the intact peptide.
Mentions: S. meliloti CCBAU 01290 was found to be an effective microsymbiont, in terms of nitrogen-fixing efficiency and nodule occupation, for major alfalfa cultivars in north China [32, 33], and has been used as rhizobial inoculant in this region. Given the non- or slow-growing feature of rhizobia in natural soils characterized by limited nutrients and various stresses [44], stationary-phase bacterial cells in MM were used to determine the phosphoproteome of S. meliloti (Fig 1). Within detected 88 unique phosphopeptides, there are 68 phosphosites with high-confidence identification (localization probability above 0.75), 16 being medium-confidence (P value between 0.75 and 0.50), and 12 low-confidence sites (P value below 0.50). Details of these phosphopeptides are listed in S1 and S2 Tables, and a typical annotated spectrum is shown in Fig 1. Among the 96 unique phosphorylated sites in 77 proteins (S2 Table), the distribution of phosphoserine (pS), phosphothreonine (pT) and phosphotyrosine (pY) is 65.6%, 29.2% and 5.2%, respectively (S2 Table). The relative frequencies of these pS/pT/pY in S. meliloti are similar to L. monocytogenes, B. subtilis and E. coli etc. [23, 24, 27], but distinct from Campylobacter jejuni, Streptomyces coelicolor, Clostridium acetobutylicum, Latococcus lactis and C. synechococcus, which have more pT or a comparable number of pT than pS [28, 45–48].

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

No MeSH data available.