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J Biol Chem. 2014 Dec 5;289(49):33945-57. doi: 10.1074/jbc.M114.597773. Epub 2014 Oct 23.

Dissection of hexosyl- and sialyltransferase domains in the bifunctional capsule polymerases from Neisseria meningitidis W and Y defines a new sialyltransferase family.

Author information

1
From the Institute of Cellular Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
2
UMR 7257, Centre National de la Recherche Scientifique, Aix-Marseille Université, 13288 Marseille, France, and the Department of Biological Sciences, King Abdulaziz University, Jeddah 21589, Saudi Arabia.
3
From the Institute of Cellular Chemistry, Hannover Medical School, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany, gerardy-schahn.rita@mh-hannover.de.

Abstract

Crucial virulence determinants of disease causing Neisseria meningitidis species are their extracellular polysaccharide capsules. In the serogroups W and Y, these are heteropolymers of the repeating units (→6)-α-d-Gal-(1→4)-α-Neu5Ac-(2→)n in NmW and (→6)-α-d-Glc-(1→4)-α-Neu5Ac-(2→)n in NmY. The capsule polymerases, SiaDW and SiaDY, which synthesize these highly unusual polymers, are composed of two predicted GT-B fold domains separated by a large stretch of amino acids (aa 399-762). We recently showed that residues critical to the hexosyl- and sialyltransferase activity are found in the predicted N-terminal (aa 1-398) and C-terminal (aa 763-1037) GT-B fold domains, respectively. Here we use a mutational approach and synthetic fluorescent substrates to define the boundaries of the hexosyl- and sialyltransferase domains. Our results reveal that the active sialyltransferase domain extends well beyond the predicted C-terminal GT-B domain and defines a new glycosyltransferase family, GT97, in CAZy (Carbohydrate-Active enZYmes Database).

KEYWORDS:

Bioinformatics; Capsule Polymerases; Enzyme Catalysis; Fluorescence-based Testing of Glycosyltransferases; Glycosyltransferase; Hexosyltransferases; Neisseria meningitidis Serogroup W and Y; Phylogenetics; Polysaccharide; Sialyltransferases

PMID:
25342753
PMCID:
PMC4256332
DOI:
10.1074/jbc.M114.597773
[Indexed for MEDLINE]
Free PMC Article

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