Molecular analysis of a complex locus from Haemophilus influenzae involved in phase-variable lipopolysaccharide biosynthesis.
A chromosomal locus, lic3, one of several involved in lipopolysaccharide (LPS) biosynthesis by Haemophilus influenzae, was cloned and its DNA sequence determined. lic3 comprises four closely apposed open reading frames (ORFs). ORF1 includes tandem repeats of the tetramer CAAT and two start codons out of frame with each other are found upstream of the repeats. ORF1 encodes a protein with no known homologues. ORF2 encodes the UDP-galactose-4-epimerase (galE) gene. ORF3 encodes a hydrophobic protein with no known homologues. ORF4 encodes the adenylate kinase (adk) gene. A deletion/insertion mutation lacking the 3' end of ORF1, all of galE, and the 5' end of ORF3 was constructed in the parent Hib strain (RM7004). These mutants had a galE phenotype, as evidenced by galactose sensitivity, altered LPS when grown in the absence of exogenous galactose, and reduced virulence in infant rats.
Maskell
D J
DJ
Molecular Infectious Diseases Group, John Radcliffe Hospital, Headington, Oxford, UK.
Szabo
M J
MJ
Butler
P D
PD
Williams
A E
AE
Moxon
E R
ER
D000263:Adenylate Kinase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002238:Carbohydrate Epimerases / Q000235:genetics / Q000378:metabolism; D004731:Endotoxins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics; D005690:Galactose / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D006192:Haemophilus Infections / Q000382:microbiology; D006193:Haemophilus influenzae / Q000235:genetics* / Q000472:pathogenicity; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016366:Open Reading Frames; D009876:Operon; D051381:Rats; D011919:Rats, Inbred Strains; D012689:Sequence Homology, Nucleic Acid; D014534:UDPglucose 4-Epimerase; D014774:Virulence
D001426:Bacterial Proteins; D004731:Endotoxins; D008070:Lipopolysaccharides; D000263:Adenylate Kinase; D002238:Carbohydrate Epimerases; D014534:UDPglucose 4-Epimerase; C020551:galactose epimerase; D005690:Galactose