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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.


Global view of identified phosphoproteins with predicated cellular localization.The cluster of orthologous group is shown. Proteins phosphorylated at Ser (black), Thr (blue), or Tyr (red) are presented in different colors; * indicates phosphorylated Thr is also identified in this protein.
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pone.0139143.g005: Global view of identified phosphoproteins with predicated cellular localization.The cluster of orthologous group is shown. Proteins phosphorylated at Ser (black), Thr (blue), or Tyr (red) are presented in different colors; * indicates phosphorylated Thr is also identified in this protein.

Mentions: Rhizobia live saprophytically in soil and occasionally form nitrogen-fixing nodules on legumes. In this study we carried out a site-specific phosphoproteomic analysis of the alfalfa microsymbiont S. meliloti growing in minimum medium at stationary phase. Ser/Thr/Tyr phosphorylation sites were identified in proteins of diverse functions regarding to COG categories (Fig 5). This not only confirmed some conserved phosphosites reported in homologous proteins of other bacteria but also revealed some previously unknown phosphorylation sites in conserved motif of proteins with important physiological roles. Some of these proteins have been demonstrated as essential elements in rhizobial adaptations to diverse stress conditions, though a considerable number of phosphoproteins have not been studied yet. Therefore, the site-specific phosphoproteome of S. meliloti obtained herein could provide valuable information for designing future experiments that address the molecular mechanism of related proteins involved in rhizobial adaptation to different environmental conditions.


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

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

Global view of identified phosphoproteins with predicated cellular localization.The cluster of orthologous group is shown. Proteins phosphorylated at Ser (black), Thr (blue), or Tyr (red) are presented in different colors; * indicates phosphorylated Thr is also identified in this protein.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0139143.g005: Global view of identified phosphoproteins with predicated cellular localization.The cluster of orthologous group is shown. Proteins phosphorylated at Ser (black), Thr (blue), or Tyr (red) are presented in different colors; * indicates phosphorylated Thr is also identified in this protein.
Mentions: Rhizobia live saprophytically in soil and occasionally form nitrogen-fixing nodules on legumes. In this study we carried out a site-specific phosphoproteomic analysis of the alfalfa microsymbiont S. meliloti growing in minimum medium at stationary phase. Ser/Thr/Tyr phosphorylation sites were identified in proteins of diverse functions regarding to COG categories (Fig 5). This not only confirmed some conserved phosphosites reported in homologous proteins of other bacteria but also revealed some previously unknown phosphorylation sites in conserved motif of proteins with important physiological roles. Some of these proteins have been demonstrated as essential elements in rhizobial adaptations to diverse stress conditions, though a considerable number of phosphoproteins have not been studied yet. Therefore, the site-specific phosphoproteome of S. meliloti obtained herein could provide valuable information for designing future experiments that address the molecular mechanism of related proteins involved in rhizobial adaptation to different environmental conditions.

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.