title: A novel locus of Yersinia enterocolitica serotype O:3 involved in lipopolysaccharide outer core biosynthesis.
abstract: Yersinia enterocolitica serotype O:3 strain 6471/76-c (YeO3-c) was sensitive to bacteriophage phi R1-37 when grown at 37 degrees C but not when grown at 22 degrees C because of steric hindrance by abundant lipopolysaccharide (LPS) O-side chain (O-antigen) expressed at 22 degrees C. The transposon library of YeO3-c was grown at 37 degrees C and screened for phage phi R1-37-resistant transposon insertion mutants. Three types of mutant were isolated: (i) phage receptor mutants expressing O-antigen (LPS-smooth), (ii) phage receptor mutants not expressing O-antigen (LPS-rough), and (iii) LPS-smooth mutants with the phage receptor constitutively sterically blocked. Mutant type (i) was characterized in detail; the transposon insertion inactivates an operon, named the trs operon. The main findings based on this mutant are: (i) the frs operon is involved in the biosynthesis of the LPS outer core in YeO3-c; the nucleotide sequence of the trs operon revealed eight novel genes showing similarly to known polysaccharide biosynthetic genes of various Gram-negative bacteria as well as to capsule biosynthesis genes of Staphylococcus aureus; (ii) the biosynthesis of the core of YeO3-c involves at least two genetic loci; (iii) the trs operon is required for the biosynthesis of the bacteriophage phi R1-37 receptor structures; (iv) the homopolymeric O-antigen of YeO3-c is ligated to the inner core in Y. enterocolitica O:3; (v) the trs operon is located between the adk-hemH and galE-gsk gene pairs in the Y. enterocolitica chromosome; and (vi) the phage phi R1-37 receptor is present in many but not in all Y. enterocolitica serotypes. The results also allow us to speculate that the trs operon is a relic of the ancestral rfb region of Y. enterocolitica O:3 carrying genes indispensable for the completion of the core polysaccharide biosynthesis.
authors.affiliation: Turku Centre for Biotechnology, University of Turku, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Skurnik
authors.forename: R
authors.initials: R
authors.lastname: Venho
authors.forename: P
authors.initials: P
authors.lastname: Toivanen
authors.forename: A
authors.initials: A
authors.lastname: al-Hendy
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001435:Bacteriophages / Q000235:genetics / Q000302:isolation & purification; D001483:Base Sequence; D004251:DNA Transposable Elements; D004269:DNA, Bacterial / Q000235:genetics; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D008070:Lipopolysaccharides / Q000096:biosynthesis* / Q000737:chemistry; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D009876:Operon; D017386:Sequence Homology, Amino Acid; D012703:Serotyping; D015008:Yersinia enterocolitica / Q000145:classification / Q000235:genetics* / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D008070:Lipopolysaccharides