title: Sinorhizobium meliloti low molecular mass phosphotyrosine phosphatase SMc02309 modifies activity of the UDP-glucose pyrophosphorylase ExoN involved in succinoglycan biosynthesis.
abstract: In Gram-negative bacteria, tyrosine phosphorylation has been shown to play a role in the control of exopolysaccharide (EPS) production. This study demonstrated that the chromosomal ORF SMc02309 from Sinorhizobium meliloti 2011 encodes a protein with significant sequence similarity to low molecular mass protein-tyrosine phosphatases (LMW-PTPs), such as the Escherichia coli Wzb. Unlike other well-characterized EPS biosynthesis gene clusters, which contain neighbouring LMW-PTPs and kinase, the S. meliloti succinoglycan (EPS I) gene cluster located on megaplasmid pSymB does not encode a phosphatase. Biochemical assays revealed that the SMc02309 protein hydrolyses p-nitrophenyl phosphate (p-NPP) with kinetic parameters similar to other bacterial LMW-PTPs. Furthermore, we show evidence that SMc02309 is not the LMW-PTP of the bacterial tyrosine-kinase (BY-kinase) ExoP. Nevertheless, ExoN, a UDP-glucose pyrophosphorylase involved in the first stages of EPS I biosynthesis, is phosphorylated at tyrosine residues and constitutes an endogenous substrate of the SMc02309 protein. Additionally, we show that the UDP-glucose pyrophosphorylase activity is modulated by SMc02309-mediated tyrosine dephosphorylation. Moreover, a mutation in the SMc02309 gene decreases EPS I production and delays nodulation on Medicago sativa roots.
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.|Department of Molecular Biology, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: Daniela B
authors.initials: DB
authors.lastname: Medeot
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: María
authors.initials: M
authors.lastname: Romina Rivero
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Cendoya
authors.affiliation: Laboratory of Computational Biology, Department of Genetics and Plant Production, Estación Experimental de Aula Dei/CSIC, Av. Montañana 1005, Zaragoza, Spain.
authors.forename: Bruno
authors.initials: B
authors.lastname: Contreras-Moreira
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: Fernando A
authors.initials: FA
authors.lastname: Rossi
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: Sonia E
authors.initials: SE
authors.lastname: Fischer
authors.affiliation: LOEWE-Center for Synthetic Microbiology, Philipps-Universität Marburg, D-35032, Marburg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Becker
authors.affiliation: Department of Natural Sciences, FCEFQyN, National University of Río Cuarto, Ruta Nacional 36 Km 601, Córdoba, Argentina.
authors.forename: Edgardo
authors.initials: E
authors.lastname: Jofré
mesh_terms: D000455:Medicago sativa / Q000382:microbiology; D055170:Plant Root Nodulation; D018517:Plant Roots / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism*; D016962:Sinorhizobium meliloti / Q000201:enzymology* / Q000378:metabolism*; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase / Q000378:metabolism*
chemical_list: D011135:Polysaccharides, Bacterial; C056779:succinoglycan; D005957:UTP-Glucose-1-Phosphate Uridylyltransferase; D017027:Protein Tyrosine Phosphatases