PMID:19289512

Citation	Deadman, ME, Hermant, P, Engskog, M, Makepeace, K, Moxon, ER, Schweda, EK and Hood, DW (2009) Lex2B, a phase-variable glycosyltransferase, adds either a glucose or a galactose to Haemophilus influenzae lipopolysaccharide. Infect. Immun. 77:2376-84
Abstract	Nontypeable Haemophilus influenzae is a commensal that frequently causes otitis media and respiratory tract infections. The lex2 locus encodes a glycosyltransferase that is phase variably expressed and contributes to the significant intrastrain heterogeneity of lipopolysaccharide (LPS) composition in H. influenzae. In serotype b strains, Lex2B adds the second beta-glucose in the oligosaccharide extension from the proximal heptose of the triheptose inner core backbone; this extension includes a digalactoside that plays a role in resistance of the bacteria to the killing effect of serum. As part of our studies of the structure and genetics of LPS in nontypeable H. influenzae, we show here that there are allelic polymorphisms in the lex2B sequence that correlate with addition of either a glucose or a galactose to the same position in the LPS molecule across strains. Through exchange of lex2 alleles between strains we show that alteration of a single amino acid at position 157 in Lex2B appears to be sufficient to direct the alternative glucosyl- or galactosyltransferase activities. Allelic exchange strains express LPS with altered structure and biological properties compared to the wild-type LPS. Thus, Lex2B contributes to both inter- and intrastrain LPS heterogeneity through its polymorphic sequences and phase-variable expression.
Links	PubMed PMC2687336 Online version:10.1128/IAI.01446-08
Keywords	Amino Acid Sequence; Amino Acid Substitution/genetics; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Child; DNA, Bacterial/chemistry; DNA, Bacterial/genetics; Galactose/metabolism; Glucose/metabolism; Glycosyltransferases/genetics; Glycosyltransferases/metabolism; Haemophilus influenzae/enzymology; Haemophilus influenzae/genetics; Haemophilus influenzae/metabolism; Humans; Lipopolysaccharides/metabolism; Molecular Sequence Data; Polymorphism, Genetic; Sequence Alignment; Sequence Analysis, DNA
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
HAEIF:C1J7J7		GO:0009103: lipopolysaccharide biosynthetic process	ECO:0000315:		P		Figures 3 and 4 show the mutant strains containing the added glucose and galactose.	complete CACAO 6054
HAEIF:C1J7J7	involved_in	GO:0009103: lipopolysaccharide biosynthetic process	ECO:0000315: mutant phenotype evidence used in manual assertion		P		Seeded From UniProt	complete

References

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