FIGURE 1.

The capsule biosynthesis gene cluster. A, schematic representation of the chromosomal locus (cps) of NmA. Products of genes forming region A are involved in the synthesis of the capsule polysaccharide and are serogroup-specific. For more information, see the Introduction (adapted from Harrison et al. (19)). B, reactions catalyzed by the gene products of csaA, csaB, and csaC (1). The putative UDP-N-acetyl-d-glucosamine-2-epimerase CsaA catalyzes the epimerization of UDP-GlcNAc to UDP-ManNAc (2). The putative capsule polymerase CsaB transfers ManNAc-1P from the resulting UDP-N-acetyl-mannosamine onto the non-reducing end of the growing CPSA (3). CsaC O-acetylates CPSA at O-3 or O-4 in the presence of the acetyl-donor acetyl-CoA.