Genetics of isoprenoid biosynthesis in Paracoccus zeaxanthinifaciens

The genes coding for all the enzymes involved in the conversion of acetyl-CoA to farnesyl diphosphate (FPP) in the zeaxanthin-producing bacterium Paracoccus zeaxanthinifaciens were cloned and characterized. Two genes encoding enzymes catalysing the condensation of two acetyl-CoA molecules to acetoacetyl-CoA were found. The six enzymes involved in the conversion of acetyl-CoA and acetoacetyl-CoA to isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP) are grouped in an operon, designated the mevalonate operon. The gene encoding the enzyme catalysing two consecutive condensations, IPP and DMAPP to geranyl diphosphate (GPP) and IPP and GPP to FPP, is not clustered with any other gene encoding an enzyme of the isoprenoid pathway. Genes encoding enzymes involved in the biosynthesis of poly-hydroxyalkanoate and non-carotenoid isoprenoids found in P. zeaxanthinifaciens are also presented.