title: Mechanism of bacitracin resistance in gram-negative bacteria that synthesize exopolysaccharides.
abstract: Four representative species from three genera of gram-negative bacteria that secrete exopolysaccharides acquired resistance to the antibiotic bacitracin by stopping synthesis of the exopolysaccharide. Xanthomonas campestris, Sphingomonas strains S-88 and NW11, and Escherichia coli K-12 secrete xanthan gum, sphingans S-88 and NW11, and colanic acid, respectively. The gumD gene in X. campestris is required to attach glucose-P to C55-isoprenyl phosphate, the first step in the assembly of xanthan. A recombinant plasmid carrying the gumD gene of X. campestris restored polysaccharide synthesis to bacitracin-resistant exopolysaccharide-negative mutants of X. campestris and Sphingomonas strains. Similarly, a newly cloned gene (spsB) from strain S-88 restored xanthan synthesis to the same X. campestris mutants. However, the intergeneric complementation did not extend to mutants of E. coli that were both resistant to bacitracin and nonproducers of colanic acid. The genetic results also suggest mechanisms for assembling the sphingans which have commercial potential as gelling and viscosifying agents.
authors.affiliation: Shin-Etsu Bio, Inc., San Diego, CA 92121.
authors.forename: T J
authors.initials: TJ
authors.lastname: Pollock
authors.forename: L
authors.initials: L
authors.lastname: Thorne
authors.forename: M
authors.initials: M
authors.lastname: Yamazaki
authors.forename: M J
authors.initials: MJ
authors.lastname: Mikolajczak
authors.forename: R W
authors.initials: RW
authors.lastname: Armentrout
mesh_terms: D001414:Bacitracin / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002240:Carbohydrate Sequence; D004305:Dose-Response Relationship, Drug; D004352:Drug Resistance, Microbial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D005816:Genetic Complementation Test; D016695:Glycosyltransferases / Q000235:genetics* / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D011106:Polyisoprenyl Phosphates / Q000378:metabolism*; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis*; D015183:Restriction Mapping; D016959:Xanthomonas campestris / Q000201:enzymology / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; C089843:GumD protein, Xanthomonas campestris; D011106:Polyisoprenyl Phosphates; D011135:Polysaccharides, Bacterial; D001414:Bacitracin; D016695:Glycosyltransferases