Molecular cloning of the Haemophilus influenzae gmhA (lpcA) gene encoding a phosphoheptose isomerase required for lipooligosaccharide biosynthesis.
We have determined that gene HI#1181 of Haemophilus influenzae is a homolog of Escherichia coli gmhA (previously designated lpcA) (J. S. Brooke and M. A. Valvano, J. Biol. Chem. 271:3608-3614, 1996), which encodes a phosphoheptose isomerase catalyzing the first step of the biosynthesis of ADP-L-glycero-D-manno heptose. Mutations in this gene are associated with a heptoseless core lipopolysaccharide which determines an increased outer membrane permeability to hydrophobic compounds. The cloned H. influenzae gmhA restored the synthesis of a complete core in the gmhA-deleted E. coli strain chi711. Amino acid sequence comparisons of the GmhA proteins of E. coli and H. influenzae with other proteins in the databases revealed the existence of a novel family of phosphosugar a1do-keto isomerases.
Brooke
J S
JS
Department of Microbiology and Immunology, University of Western Ontario, London, Canada.
Valvano
M A
MA
D019747:Aldose-Ketose Isomerases; D000595:Amino Acid Sequence; D001483:Base Sequence; D002238:Carbohydrate Epimerases / Q000737:chemistry / Q000235:genetics*; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics*; D008070:Lipopolysaccharides / Q000096:biosynthesis*; D008969:Molecular Sequence Data
D008070:Lipopolysaccharides; C023023:lipid-linked oligosaccharides; D002238:Carbohydrate Epimerases; D019747:Aldose-Ketose Isomerases; C023917:phosphoheptose isomerase