Biosynthetic genes and enzymes of isoprenoids produced by actinomycetes

Abstract

Most isoprenoids have been isolated from eukaryotes such as plants and fungi. However, actinomycete strains, which are known to produce many kinds of nonribosomal peptides and polyketides, were also reported to produce isoprenoids. We now realize that many actinomycete strains possess many isoprenoid biosynthetic genes since genome data base has enabled us to examine the presence of candidate genes. Moreover, by in vitro assay with recombinant enzymes and heterologous expression of the gene cluster, we can know structures of metabolites synthesized by the gene product. In many cases, isoprenoid moieties of compounds produced by actinomycetes are attached to other moieties, such as a polyketide, an aromatic ring, an amino acid, etc., that are synthesized via pathways independent of isoprenoid synthesis to give the so-called isoprenoid hybrid compounds, in contrast to eukaryotic isoprenoids, which usually have cyclic structures that are formed by cyclization of GDP, FDP, and GGDP. The structures of prokaryotic isoprenoids, therefore, are unique and different from those of eukaryotic origin. In this chapter, a structural diversity of isoprenoids produced by actinomycetes is summarized together with biosynthetic genes and enzymes responsible for them.