Evolution and Distribution of C-Cyclitol Synthases in Prokaryotes and Eukaryotes.

2-Epi-5-epi-valiolone synthase (EEVS), a C-sugar phosphate cyclase (SPC) homologous to 3-dehydroquinate synthase (DHQS), was discovered during studies of the biosynthesis of the CN-aminocyclitol family of natural products. EEVS was originally thought to be present only in certain actinomycetes, but analyses of genome sequences showed that it is broadly distributed in both prokaryotes and eukaryotes, including vertebrates. Another SPC, desmethyl-4-deoxygadusol synthase (DDGS), was later discovered as being involved in the biosynthesis of mycosporine-like amino acid sunscreen compounds.