The Neisseria meningitidis serogroup A capsular polysaccharide O-3 and O-4 acetyltransferase.
Neisseria meningitidis serogroup A capsular polysaccharide (CPS) is composed of a homopolymer of O-acetylated, alpha1-->6-linked ManNAc 1-phosphate that is distinct from the capsule structures of the other meningococcal disease-causing serogroups, B, C, Y, and W-135. The serogroup A capsule biosynthetic genetic cassette consists of four open reading frames, mynA-D (sacA-D), that are specific to serogroup A, but the functions of these genes have not been well characterized. mynC was found to encode an inner membrane-associated acetyltransferase that is responsible for the O-acetylation of the CPS of serogroup A. The wild-type CPS as revealed by 1H NMR had 60-70% O-acetylated ManNAc residues that contained acetyl groups at O-3, with some species acetylated at O-4 and at both O-3 and O-4. A non-polar mynC mutant generated by introducing an aphA-3 kanamycin resistance cassette produced CPS with no O-acetylation. A serogroup A capsule-specific monoclonal antibody was shown to recognize the wild-type O-acetylated CPS, but not the CPS of the mynC mutant, which lacked O-acetylation. MynC was C-terminally His-tagged and overexpressed in Escherichia coli to obtain the predicted approximately 26-kDa protein. The acetyltransferase activity of purified MynC was demonstrated in vitro using [14C]acetyl-CoA. MynC O-acetylated the O-acetylated CPS of the mynC mutant and further acetylated the wild-type CPS of serogroup A meningococci, but not the CPS of serogroup B or C meningococci. Genetic complementation of the mynC mutant confirmed the function of MynC as the serogroup A CPS O-3 and O-4 acetyltransferase. MynC represents a new subclass of O-acetyltransferases that utilize acetyl-CoA to decorate the D-mannosamine capsule of N. meningitidis serogroup A.
Gudlavalleti
Seshu K
SK
Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
Datta
Anup K
AK
Tzeng
Yih-Ling
YL
Noble
Corie
C
Carlson
Russell W
RW
Stephens
David S
DS
D000123:Acetyltransferases / Q000737:chemistry* / Q000378:metabolism; D000911:Antibodies, Monoclonal / Q000737:chemistry; D016667:Bacterial Capsules / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D002845:Chromatography; D003600:Cytosol / Q000378:metabolism; D019992:Databases as Topic; D004305:Dose-Response Relationship, Drug; D004351:Drug Resistance; D004797:Enzyme-Linked Immunosorbent Assay; D004926:Escherichia coli / Q000378:metabolism; D005816:Genetic Complementation Test; D006595:Hexosamines / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007612:Kanamycin / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008957:Models, Genetic; D009154:Mutation; D009345:Neisseria meningitidis / Q000378:metabolism*; D009596:Nitrophenols / Q000737:chemistry; D016133:Polymerase Chain Reaction; D011108:Polymers; D011135:Polysaccharides, Bacterial / Q000737:chemistry*; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D013347:Subcellular Fractions; D013997:Time Factors
D000911:Antibodies, Monoclonal; D006595:Hexosamines; D009596:Nitrophenols; D011108:Polymers; D011135:Polysaccharides, Bacterial; C008322:mannosamine; D007612:Kanamycin; C008642:4-nitrophenyl acetate; D000123:Acetyltransferases