Send to

Choose Destination
J Biol Chem. 2002 Apr 26;277(17):14598-611. Epub 2002 Feb 12.

Haemophilus influenzae type b strain A2 has multiple sialyltransferases involved in lipooligosaccharide sialylation.

Author information

Department of Microbiology, University of Iowa, Iowa City, Iowa 52242, USA.


The lipooligosaccharide (LOS) of Haemophilus influenzae contains sialylated glycoforms, and a sialyltransferase, Lic3A, has been previously identified. We report evidence for two additional sialyltransferases, SiaA, and LsgB, that affect N-acetyllactosamine containing glycoforms. Mutations in genes we have designated siaA and lsgB affected only the sialylated glycoforms containing N-acetylhexosamine. A mutation in siaA resulted in the loss of glycoforms terminating in sialyl-N-acetylhexosamine and the appearance of higher molecular weight glycoforms, containing the addition of phosphoethanolamine, N-acetylgalactosamine, and N-acetylneuraminic acid. Chromosomal complementation of the siaA mutant resulted in the expression of the original sialylated LOS phenotype. A mutation in lic3A resulted in the loss of sialylation only in glycoforms lacking N-acetylhexosamine and had no effect on sialylation of the terminal N-acetyllactosamine epitope. A double mutant in siaA and lic3A resulted in the complete loss of sialylation of the terminal N-acetyllactosamine epitope and expression of the higher molecular weight sialylated glycoforms seen in the siaA mutant. Mutation of lsgB resulted in persistence of sialylated glycoforms but a reduction in N-acetyllactosamine containing glycoforms. A triple mutant of siaA, lic3A, and lsgB contained no sialylated glycoforms. These results demonstrate that the sialylation of the LOS of H. influenzae is a complex process involving multiple sialyltransferases.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for HighWire
Loading ...
Support Center