lpt6, a gene required for addition of phosphoethanolamine to inner-core lipopolysaccharide of Neisseria meningitidis and Haemophilus influenzae.
We previously described a gene, lpt3, required for the addition of phosphoethanolamine (PEtn) at the 3 position on the beta-chain heptose (HepII) of the inner-core Neisseria meningitidis lipopolysaccharide (LPS), but it has long been recognized that the inner-core LPS of some strains possesses PEtn at the 6 position (PEtn-6) on HepII. We have now identified a gene, lpt6 (NMA0408), that is required for the addition of PEtn-6 on HepII. The lpt6 gene is located in a region previously identified as Lgt-3 and is associated with other LPS biosynthetic genes. We screened 113 strains, representing all serogroups and including disease and carriage strains, for the lpt3 and lpt6 genes and showed that 36% contained both genes, while 50% possessed lpt3 only and 12% possessed lpt6 only. The translated amino acid sequence of lpt6 has a homologue (72.5% similarity) in a product of the Haemophilus influenzae Rd genome sequence. Previous structural studies have shown that all H. influenzae strains investigated have PEtn-6 on HepII. Consistent with this, we found that, among 70 strains representing all capsular serotypes and nonencapsulated H. influenzae strains, the lpt6 homologue was invariably present. Structural analysis of LPS from H. influenzae and N. meningitidis strains where lpt6 had been insertionally inactivated revealed that PEtn-6 on HepII could not be detected. The translated amino acid sequences from the N. meningitidis and H. influenzae lpt6 genes have conserved residues across their lengths and are part of a family of proven or putative PEtn transferases present in a wide range of gram-negative bacteria.
Molecular Infectious Diseases Group, Dept. of Pediatrics, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, United Kingdom. claire.wright@paediatrics.ox.ac.uk.
J Claire
JC
Wright
Derek W
DW
Hood
Gaynor A
GA
Randle
Katherine
K
Makepeace
Andrew D
AD
Cox
Jianjun
J
Li
Ronald
R
Chalmers
James C
JC
Richards
E Richard
ER
Moxon
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D004983:Ethanolamines / Q000378:metabolism*; D006193:Haemophilus influenzae / Q000235:genetics* / Q000378:metabolism; D008070:Lipopolysaccharides / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009345:Neisseria meningitidis / Q000235:genetics* / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism
D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D004983:Ethanolamines; D008070:Lipopolysaccharides; C005448:phosphorylethanolamine; D017853:Phosphotransferases (Alcohol Group Acceptor)