Abstract
The capsular polysaccharide is a critical virulence factor for group B streptococci associated with human infections, yet little is known about capsule biosynthesis. We detected CMP-Neu5Ac synthetase, the enzyme which activates N-acetylneuraminic acid (Neu5Ac, or sialic acid) for transfer to the nascent capsular polysaccharide, in multiple group B streptococcus serotypes, all of which elaborate capsules containing Neu5Ac. CMP-Neu5Ac synthetase isolated from a high-producing type Ib strain was purified 87-fold. The enzyme had apparent Km values of 7.6 for Neu5Ac and 1.4 for CTP and a pH optimum of 8.3 to 9.4, required magnesium, and was stimulated by dithiothreitol. This is the first characterization of an enzyme involved in group B streptococcus capsular polysaccharide biosynthesis.
MeSH Terms
Cytidine Triphosphate/metabolism
Escherichia coli/enzymology
N-Acetylneuraminic Acid
N-Acylneuraminate Cytidylyltransferase/isolation & purification,metabolism
Neisseria meningitidis/enzymology
Serotyping
Sialic Acids/metabolism
Streptococcus agalactiae/enzymology,immunology
Chemicals
Sialic Acids
Cytidine Triphosphate
N-Acylneuraminate Cytidylyltransferase
N-Acetylneuraminic Acid
Authors & Affiliations
2 authors, click to expand affiliations / ORCID
Haft R F
Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115.
Wessels M R
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