The siaA gene involved in capsule polysaccharide biosynthesis of Neisseria meningitidis B codes for N-acylglucosamine-6-phosphate 2-epimerase activity

• Published in: FEMS microbiology letters Vol. 184; no. 2; pp. 161 - 164
• Main Authors: Petersen, Michael, Fessner, Wolf-Dieter, Frosch, Matthias, Lüneberg, Edeltraud
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.03.2000; Blackwell; Oxford University Press
• Subjects: Acetylglucosamine - metabolism; Bacterial Capsules - biosynthesis; Bacterial Capsules - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Bacteriology; Biochemical analysis; Biological and medical sciences; Biosynthesis; Capsule polysaccharide; Carbohydrate Epimerases - genetics; Carbohydrate Epimerases - metabolism; E coli; Enzymatic activity; Epimerase; Fundamental and applied biological sciences. Psychology; Genes, Bacterial; Genetics; GlcNAc‐6‐phosphate 2‐epimerase; Glucosamine; Isomerism; Isomerization; ManNAc; Microbiology; N-Acetylglucosamine; N-Acetylneuraminic Acid - metabolism; N-Acylglucosamine-6-phosphate 2-epimerase; Neisseria meningitidis; Neisseria meningitidis - genetics; Neisseria meningitidis - metabolism; Polymerization; Polysaccharides; Racemases and Epimerases; Recombinant Proteins - metabolism; SiaA; Sialic acid biosynthesis; Substrates; SiaA; ManNAc; Capsule polysaccharide; Sialic acid biosynthesis; GlcNAc-6-phosphate 2-epimerase; Sialic acid; Enzyme; Neisseriaceae; Biosynthesis; Neisseria meningitidis; Microorganism capsule; Isomerases; Enzymatic activity; Gene; N-Acylglucosamine-6-phosphate 2-epimerase; Bacteria; Micrococcales; Polysaccharide
• ISSN: 0378-1097; 1574-6968
• DOI: 10.1111/j.1574-6968.2000.tb09008.x

Abstract The capsule polysaccharide of Neisseria meningitidis serogroup B is composed of a homopolymer of α-2→8 linked N-acetyl-neuraminic acid (sialic acid). The enzymes required for sialic acid biosynthesis and polymerization are encoded in region A of the capsule gene complex. We here describe the enzymatic activity of the siaA gene product as determined by biochemical analysis. siaA was overexpressed in Escherichia coli and the SiaA protein was purified to homogeneity. Enzymatic assays revealed that SiaA did not accept N-acetyl-glucosamine as substrate, but only N-acetyl-glucosamine-6-phosphate (EC 5.1.3.9). SiaA catalyzes the isomerization of N-acetyl-glucosamine-6-phosphate to form N-acetyl-mannosamine-6-phosphate. This reaction represents the first step in capsule biosynthesis of N. meningitidis B.