title: Rhizobium leguminosarum bv. trifolii PssP protein is required for exopolysaccharide biosynthesis and polymerization.
abstract: Rhizobium leguminosarum bv. trifolii produces an acidic exopolysaccharide (EPS) that is important for the induction of nitrogen-fixing nodules on clover. Recently, three genes, pssN, pssO, and pssP, possibly involved in EPS biosynthesis and polymerization were identified. The predicted protein product of the pssP gene shows a significant sequence similarity to other proteins belonging to the PCP2a family that are involved in the synthesis of high-molecular-weight EPS. An R. leguminosarum bv. trifolii TA1 mutant with the entire coding region of pssP deleted did not produce the EPS. A pssP mutant with the 5' end of the gene disrupted produced exclusively low-molecular-weight EPS. A mutant that synthesized a functional N-terminal periplasmic domain but lacked the C-terminal part of PssP produced significantly reduced amounts of EPS with a slightly changed low to high molecular form ratio. Mutants affected in the PssP protein carrying a stable plasmid with a constitutively expressed gusA gene induced nodules on red clover that were not fully occupied by bacteria. A mutant with the entire pssP gene deleted infected only a few plant cells in the nodule. The pssP promoter-gusA reporter fusion was active in bacteroids during nodule development.
authors.affiliation: Department of General Microbiology, M. Curie-Skłodowska University, Lublin, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Mazur
authors.forename: Jarosław E
authors.initials: JE
authors.lastname: Król
authors.forename: Jerzy
authors.initials: J
authors.lastname: Wielbo
authors.forename: Teresa
authors.initials: T
authors.lastname: Urbanik-Sypniewska
authors.forename: Anna
authors.initials: A
authors.lastname: Skorupska
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D017353:Gene Deletion; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D016254:Mutagenesis, Insertional; D009154:Mutation; D009586:Nitrogen Fixation / Q000235:genetics; D010944:Plants / Q000382:microbiology; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000737:chemistry; D016961:Rhizobium leguminosarum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D013559:Symbiosis; D014158:Transcription, Genetic; D014170:Transformation, Genetic; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011135:Polysaccharides, Bacterial; D001616:beta-Galactosidase