Proposed pathway of triterpenoid carotenoid biosynthesis in Staphylococcus aureus: evidence from a study of mutants

Mutants of Staphylococcus aureus were isolated which showed changes in pigment composition compared with the parent strain. On the basis of differences in their triterpenoid carotenoid composition they were classified into seven types. In five of these types, there appeared to be a blockage in the biosynthetic pathway which resulted in the absence of some products and accumulation of others. The changes in the other two types appeared to be a consequence of some change in regulation. A scheme for the biosynthesis of triterpenoid carotenoids is presented in which the first C30 intermediate, 4,4'-diapophytoene, is converted via 4,4'-diapophytofluene, 4,4'-diapo-zeta-carotene, 4,4'-diaponeurosporene, 4,4'-diaponeurosporenal, 4,4'-diaponeurosporenoic acid, and glucosyl-diaponeurosporenoate to the major pigment staphyloxanthin.