title: Analysis of the syrP gene, which regulates syringomycin synthesis by Pseudomonas syringae pv. syringae.
abstract: Syringomycin is a lipodepsinonapeptide phytotoxin synthesized by Pseudomonas syringae pv. syringae on multienzymatic peptide synthetases. Sequence analysis of the interval between the syrB and syrD genes of P. syringae pv. syringae strain B301D revealed a 1,059-bp open reading frame (ORF), designated syrP. The predicted product of this ORF was a 39.6-kDa protein consisting of 353 amino acid residues. Searches of protein sequence databases demonstrated that SyrP was most similar to histidine kinases such as the CheA regulatory protein of Escherichia coli. The predicted SyrP sequence was aligned with the N terminus of CheA, a region corresponding to the phosphotransfer and acceptor domains of CheA. The SyrP region that aligns with the phosphotransfer domain of CheA contained a His at position 101 which is flanked by a weak consensus sequence of the unorthodox sensory kinase subfamily of two-component regulatory systems. Strain B301D-31, obtained by site-directed insertional mutagenesis of the syrP gene, exhibited an unusual pleiotropic phenotype including a failure to produce syringomycin in liquid media in contrast to production of elevated levels of the toxin on agar media. The syrP mutant was relieved of the suppression of toxin production that accompanies inorganic phosphate concentrations of > 1 mM on agar media. Nevertheless, the syrP mutant was substantially less virulent than the wild-type strain in pathogenicity assays in cherry fruits. These results suggest that the syrP gene encodes a regulatory protein that participates in a phosphorylation cascade controlling syringomycin production and virulence in P. syringae pv. syringae.
authors.affiliation: Department of Plant Pathology, Washington State University, Pullman 99164-6430, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Zhang
authors.forename: N B
authors.initials: NB
authors.lastname: Quigley
authors.forename: D C
authors.initials: DC
authors.lastname: Gross
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002874:Chromosome Mapping; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D005638:Fruit / Q000382:microbiology; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006639:Histidine / Q000235:genetics; D000071677:Histidine Kinase; D008565:Membrane Proteins / Q000235:genetics; D000072236:Methyl-Accepting Chemotaxis Proteins; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D010453:Peptide Synthases; D011494:Protein Kinases / Q000235:genetics; D011549:Pseudomonas / Q000235:genetics* / Q000472:pathogenicity; D011995:Recombination, Genetic; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; C107147:SyrP protein, Pseudomonas syringae; C084291:syrD protein, Pseudomonas syringae; C032677:syringomycin; D006639:Histidine; D011494:Protein Kinases; D000071677:Histidine Kinase; C000607608:cheA protein, E coli; D010453:Peptide Synthases; C094581:SYRB1 protein, Pseudomonas syringae