| Type: | Family | Name: | Polyketide synthesis cyclase |
| Description: | Aromatic polyketides are assembled by a type II (iterative) polyketide synthases (PKSs) in bacteria. Type II PKS complexes consist of several monofunctional or bifunctional proteins which produce polyketide chains of variable but defined length from a specific starter unit and a number of extender units. They also specify the initial regiospecific folding and cyclization pattern of nascent polyketides either through the action of a cyclase (CYC) subunit or through the combined action of site-specific ketoreductase and CYC subunits [, ]. This family represents a number of cyclases involved in polyketide synthesis in a number of actinobacterial species.Tetracenomycin F2 cyclase (TcmI) catalyses an aromatic rearrangement in the biosynthetic pathaway of tetracenomycin C from Streptomyces glaucescens. The protein is a homodimer where each subunit forms a beta-alpha-beta fold belonging to the ferrodoxin fold superfamily []. Four strands of antiparallel sheets and a layer of alpha helices create a cavity which was proposed to be the active site. This structure shows strong topological similarity to a polyketide monoxygenase () from S. coelicolor which functions in the actinorhodin biosynthesic pathway []. It was suggested, therefore, that this fold is well suited to serve as a framework for rearrangements and chemical modification of polyaromatic substrates. | Short Name: | Polyketide_synth_cyclase |
