CMP-sialic acid synthetase of the nucleus - ScienceDirect
Neisseria meningitidis B is a leading cause of bacterial meningitis for which there is no available vaccine. These bacteria express a linear homopolymer of α-2,8-linked sialic acid (1) as part of their capsular polysaccharides. In humans, polysialic acid (1) expression occurs early in development and is down regulated by about two years of age suggesting that its functional role in bacteria may be related to host mimicry.– The bacteria may employ this polymer in cellular interactions that permit infection. Recently, we have focused our attention on developing methods for the synthesis of substrate-based inhibitors of enzymes involved in the biosynthesis of polysialic acids, which include CMP-sialic acid synthetases (CSS) and polysialyltransferases (PST). CSS is a bisubstrate enzyme that utilizes both sialic acid and cytidine triphosphate (CTP) as substrates in the production of CMP-sialic acid, which in turn is a substrate for PST, (). Activation of sialic acid to CMP-sialic acid is an essential step in the biosynthesis of sialoglyconjugates that is conserved from bacteria to humans: however, eukaryotic CSS are localized in the nuclear compartment whereas the bacterial enzymes are cytoplasmic. This fundamental difference offers the possibility of achieving selective inhibition as a function of nuclear transport. Presumably, inhibitors incapable of permeating the nuclear membrane would not inhibit mammalian enzymes. Development of substrate analogs of CSS enzymes as inhibitors and/or molecular probes represents an important area of investigation for potential drug development, as incorporation of sialic acid into capsular polysaccharides is required for the conversion of N. meningitidis to a serum resistant phenotype.–
Chemoenzymatic synthesis of CMP–sialic acid …
Specific Activity One unit of CMP-sialic acid synthetase is defined as the amount of enzyme required to produce 1 µmole of CMP-sialic acid in 1 minute at 37 ¡C, pH 9.5, from CTP & sialic acid.
This enzyme catalyzes the synthesis of CMP sialic acid from CTP & sialic acid.
The resulting molecule can then be covalently attached to an oligosaccharide by sialic acid transferase.