A single nucleotide exchange in the wzy gene is responsible for the semirough O6 lipopolysaccharide phenotype and serum sensitivity of Escherichia coli strain Nissle 1917.
Structural analysis of lipopolysaccharide (LPS) isolated from semirough, serum-sensitive Escherichia coli strain Nissle 1917 (DSM 6601, serotype O6:K5:H1) revealed that this strain's LPS contains a bisphosphorylated hexaacyl lipid A and a tetradecasaccharide consisting of one E. coli O6 antigen repeating unit attached to the R1-type core. Configuration of the GlcNAc glycosidic linkage between O-antigen oligosaccharide and core (beta) differs from that interlinking the repeating units in the E. coli O6 antigen polysaccharide (alpha). The wa(*) and wb(*) gene clusters of strain Nissle 1917, required for LPS core and O6 repeating unit biosyntheses, were subcloned and sequenced. The DNA sequence of the wa(*) determinant (11.8 kb) shows 97% identity to other R1 core type-specific wa(*) gene clusters. The DNA sequence of the wb(*) gene cluster (11 kb) exhibits no homology to known DNA sequences except manC and manB. Comparison of the genetic structures of the wb(*)(O6) (wb(*) from serotype O6) determinants of strain Nissle 1917 and of smooth and serum-resistant uropathogenic E. coli O6 strain 536 demonstrated that the putative open reading frame encoding the O-antigen polymerase Wzy of strain Nissle 1917 was truncated due to a point mutation. Complementation with a functional wzy copy of E. coli strain 536 confirmed that the semirough phenotype of strain Nissle 1917 is due to the nonfunctional wzy gene. Expression of a functional wzy gene in E. coli strain Nissle 1917 increased its ability to withstand antibacterial defense mechanisms of blood serum. These results underline the importance of LPS for serum resistance or sensitivity of E. coli.
Grozdanov
Lubomir
L
Institut für Molekulare Infektionsbiologie, Bayerische Julius-Maximilians-Universität Würzburg, Röntgenring 11, D-97070 Würzburg, Germany.
Zähringer
Ulrich
U
Blum-Oehler
Gabriele
G
Brade
Lore
L
Henne
Anke
A
Knirel
Yuriy A
YA
Schombel
Ursula
U
Schulze
Jürgen
J
Sonnenborn
Ulrich
U
Gottschalk
Gerhard
G
Hacker
Jörg
J
Rietschel
Ernst T
ET
Dobrindt
Ulrich
U
D000483:Alleles; D001483:Base Sequence; D002240:Carbohydrate Sequence; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology* / Q000302:isolation & purification; D005816:Genetic Complementation Test; D006602:Hexosyltransferases / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008050:Lipid A / Q000737:chemistry; D008070:Lipopolysaccharides / Q000737:chemistry*; D008969:Molecular Sequence Data; D005810:Multigene Family; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods; D009711:Nucleotides; D019081:O Antigens / Q000737:chemistry; D009844:Oligosaccharides / Q000737:chemistry; D010641:Phenotype; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D004269:DNA, Bacterial; D008050:Lipid A; D008070:Lipopolysaccharides; D009711:Nucleotides; D019081:O Antigens; D009844:Oligosaccharides; D006602:Hexosyltransferases; C085652:O-antigen polymerase