A mechanism-based fluorescence transfer assay for examining ketosynthase selectivity.
Since their discovery, polyketide synthases have received massive attention from researchers hoping to harness their potential as a platform for generating new and improved therapeutics. Despite significant strides toward this end, inherent specificities within the enzymes responsible for polyketide production have severely limited these efforts. We have developed a mechanism-based, fluorescence transfer assay for a key enzyme component of all polyketide synthases, the ketosynthase domain. As demonstrated, this method can be used with both ketosynthase-containing didomains and full modules. As proof of principle, the ketosynthase domain from module 6 of the 6-deoxyerythronolide synthase is examined for its ability to accept a variety of simple thioester substrates. Consistent with its natural hexaketide substrate, we find that this ketosynthase prefers longer, α-branched thioesters and its ability to distinguish these structural features is quite remarkable. Substrate electronics are also tested via a variety of p-substituted aromatic groups. In all, we expect this technique to find considerable use in the field of polyketide biosynthesis and engineering due to its extraordinary simplicity and very distinct visible readout.
Department of Chemistry, University of Massachusetts, Amherst, 01003, USA.
Gitanjeli
G
Prasad
Lawrence S
LS
Borketey
Tsung-Yi
TY
Lin
Nathan A
NA
Schnarr
D000213:Acyl Carrier Protein / Q000737:chemistry / Q000378:metabolism; D003543:Cysteamine / Q000031:analogs & derivatives; D004926:Escherichia coli / Q000737:chemistry / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism; D004952:Esters / Q000737:chemistry / Q000378:metabolism; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D048630:Polyketide Synthases / Q000737:chemistry / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000737:chemistry / Q000378:metabolism
D000213:Acyl Carrier Protein; D029968:Escherichia coli Proteins; D004952:Esters; D013438:Sulfhydryl Compounds; D003543:Cysteamine; D048630:Polyketide Synthases