The role of lic2B in lipopolysaccharide biosynthesis in Haemophilus influenzae strain Eagan

• Published in: Carbohydrate research 2011-07, Vol.346 (10), p.1262-1266
• Main Authors: Twelkmeyer, Brigitte, Deadman, Mary E., Haque, Ehsanul, Li, Jianjun, Hood, Derek W., Schweda, Elke K.H.
• Format: Article
• Language: English
• Subjects: Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; biosynthesis; Carbohydrate Sequence; genes; glucose; Glucosyltransferase; Glucosyltransferases - metabolism; Haemophilus Infections - metabolism; Haemophilus Infections - pathology; Haemophilus influenzae; Haemophilus influenzae - classification; Haemophilus influenzae - genetics; Haemophilus influenzae - metabolism; Humans; knockout mutants; lic2B; Lipopolysaccharide; lipopolysaccharides; Lipopolysaccharides - biosynthesis; Lipopolysaccharides - chemistry; loci; Mass Spectrometry; Medicin och hälsovetenskap; Molecular Sequence Data; mutation; nuclear magnetic resonance spectroscopy
• ISSN: 0008-6215; 1873-426X; 1873-426X
• DOI: 10.1016/j.carres.2011.04.016

Lipopolysaccharide (LPS) biosynthesis in Haemophilus influenzae involves genes from the lic2 locus that are required for chain extension from the middle heptose (HepII) of the conserved triheptosyl inner-core moiety. Lic2C initiates the process by attaching the first glucose to HepII, but the gene encoding for the enzyme adding the next β- d-Glc p- is uncharacterized. Lic2B is the candidate glucosyltransferase; however, in previous investigations, mutation of lic2B resulted in no hexose extension from HepII, likely due to a polar effect on the lic2C gene. In this study we complemented a lic2B knock-out mutant of H. influenzae strain Eagan with a functional lic2C gene and investigated its LPS by mass spectrometry and 2D NMR spectroscopy. Lic2B was found to encode a glucosyltransferase responsible for the linkage of β- d-Glc p-(1→4)-α- d-Glc p-(1→ extending from O-3 of the central heptose of the triheptosyl inner-core moiety, l-α- d-Hep p-(1→2)-[ PEtn→6]- l-α- d-Hep p-(1→3)- l-α- d-Hep p-(1→5)-[ PPEtn→4]-α-Kdo-(2→6)-lipid A.