title: Ketoreduction in mycolactone biosynthesis: insight into substrate specificity and stereocontrol from studies of discrete ketoreductase domains in vitro.
abstract: Mycolactone, a polyketide toxin responsible for the extensive tissue destruction seen in Buruli ulcer, is assembled on a modular polyketide synthase (PKS). Despite operating on structurally different intermediates during synthesis, many of the ketoreductase (KR) domains of the mycolactone (MLS) PKS have identical sequences. This suggests that these enzymes might exhibit an unusually high level of substrate promiscuity. However, we show here that when recombinant mycolactone KR domains are tested with a range of surrogate substrates, their specificity closely matches that of KR domains derived from other PKS systems. In addition, our findings reinforce the role of substrate tethering for achieving stereochemical control in modular PKSs by affecting the delicate energetics of ketoreduction.
authors.affiliation: Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge, CB2 1GA, UK.
authors.forename: Shilpa
authors.initials: S
authors.lastname: Bali
authors.forename: Kira J
authors.initials: KJ
authors.lastname: Weissman
mesh_terms: D001427:Bacterial Toxins / Q000096:biosynthesis*; D020134:Catalytic Domain; D007659:Ketones / Q000737:chemistry*; D018942:Macrolides; D015394:Molecular Structure; D010084:Oxidation-Reduction; D048630:Polyketide Synthases / Q000737:chemistry* / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D001427:Bacterial Toxins; D007659:Ketones; D018942:Macrolides; D011994:Recombinant Proteins; C117218:mycolactone; D048630:Polyketide Synthases