title: Cloning and characterization of two Serratia marcescens genes involved in core lipopolysaccharide biosynthesis.
abstract: Bacteriocin 28b from Serratia marcescens binds to Escherichia coli outer membrane proteins OmpA and OmpF and to lipopolysaccharide (LPS) core (J. Enfedaque, S. Ferrer, J. F. Guasch, J. Tomás, and M. Requé, Can. J. Microbiol. 42:19-26, 1996). A cosmid-based genomic library of S. marcescens was introduced into E. coli NM554, and clones were screened for bacteriocin 28b resistance phenotype. One clone conferring resistance to bacteriocin 28b and showing an altered LPS core mobility in polyacrylamide gel electrophoresis was found. Southern blot experiments using DNA fragments containing E. coli rfa genes as probes suggested that the recombinant cosmid contained S. marcescens genes involved in LPS core biosynthesis. Subcloning, isolation of subclones and Tn5tac1 insertion mutants, and sequencing allowed identification of two apparently cotranscribed genes. The deduced amino acid sequence from the upstream gene showed 80% amino acid identity to the KdtA protein from E. coli, suggesting that this gene codes for the 3-deoxy-manno-octulosonic acid transferase of S. marcescens. The downstream gene (kdtX) codes for a protein showing 20% amino acid identity to the Haemophilus influenzae kdtB gene product. The S. marcescens KdtX protein is unrelated to the KdtB protein of E. coli K-12. Expression of the kdtX gene from S. marcescens in E. coli confers resistance to bacteriocin 28b.
authors.affiliation: Department of Microbiology and Parasitology, Health Sciences Division, Faculty of Pharmacy, University of Barcelona, Spain.
authors.forename: J F
authors.initials: JF
authors.lastname: Guasch
authors.forename: N
authors.initials: N
authors.lastname: Piqué
authors.forename: N
authors.initials: N
authors.lastname: Climent
authors.forename: S
authors.initials: S
authors.lastname: Ferrer
authors.forename: S
authors.initials: S
authors.lastname: Merino
authors.forename: X
authors.initials: X
authors.lastname: Rubires
authors.forename: J M
authors.initials: JM
authors.lastname: Tomas
authors.forename: M
authors.initials: M
authors.lastname: Regué
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001430:Bacteriocins / Q000494:pharmacology; D001483:Base Sequence; D003001:Cloning, Molecular; D004352:Drug Resistance, Microbial; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012706:Serratia marcescens / Q000235:genetics*; D014166:Transferases / Q000145:classification / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; C101906:KdtX protein, Serratia marcescens; D008070:Lipopolysaccharides; C076729:bss protein, bacteria; D014166:Transferases; C019917:3-deoxy-D-manno-octulosonate transferase