A bifunctional enzyme in a single gene catalyzes the incorporation of GlcN into the Aeromonas core lipopolysaccharide.
The core lipopolysaccharide (LPS) of Aeromonas hydrophila AH-3 and Aeromonas salmonicida A450 is characterized by the presence of the pentasaccharide alpha-d-GlcN-(1-->7)-l-alpha-d-Hep-(1-->2)-l-alpha-d-Hep-(1-->3)-l-alpha-d-Hep-(1-->5)-alpha-Kdo. Previously it has been suggested that the WahA protein is involved in the incorporation of GlcN residue to outer core LPS. The WahA protein contains two domains: a glycosyltransferase and a carbohydrate esterase. In this work we demonstrate that the independent expression of the WahA glycosyltransferase domain catalyzes the incorporation of GlcNAc from UDP-GlcNAc to the outer core LPS. Independent expression of the carbohydrate esterase domain leads to the deacetylation of the GlcNAc residue to GlcN. Thus, the WahA is the first described bifunctional glycosyltransferase enzyme involved in the biosynthesis of core LPS. By contrast in Enterobacteriaceae containing GlcN in their outer core LPS the two reactions are performed by two different enzymes.
Jimenez
Natalia
N
Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Diagonal 645, 08071 Barcelona, Spain.
Vilches
Silvia
S
Lacasta
Anna
A
Regué
Miguel
M
Merino
Susana
S
Tomás
Juan M
JM
D000117:Acetylglucosamine / Q000378:metabolism; D000333:Aeromonas / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D016980:Aeromonas hydrophila / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D048409:Aeromonas salmonicida / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D002384:Catalysis; D004591:Electrophoresis, Polyacrylamide Gel; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism*; D016695:Glycosyltransferases / Q000235:genetics / Q000378:metabolism*; D006867:Hydrolases / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D007700:Kinetics; D008070:Lipopolysaccharides / Q000378:metabolism*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017386:Sequence Homology, Amino Acid
D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D009097:Multienzyme Complexes; D016695:Glycosyltransferases; D006867:Hydrolases; D004950:Esterases; D005944:Glucosamine; D000117:Acetylglucosamine