The Bifunctional Glyceryl Transferase/Phosphatase OzmB Belonging to the HAD Superfamily That Diverts 1,3-Bisphosphoglycerate into Polyketide Biosynthesis

摘要

FK520,tautomycin,lankamycin,concanamycin,geldanamycin,zwittermycin,maytansinoids,and oxazolomycin are polyketide natural products that have one or more glycolytic derived units in their backbone.The biosynthetic gene clusters for FK520,tautomycin,oxazolomycin,concanamycin,geldanamycin,and the maytansinoid ansamitosin P-3 have been identified.1 Each of these clusters contains a gene whose deduced product (a 40 kDa protein) belongs to the haloacid dehalogenase (HAD) superfamily (Figure S1) and is the most likely candidate for diverting a portion of the glycolytic pool into secondary metabolite polyketide biosynthesis.In this paper,we show that OzmB,a member of the HAD family of proteins from the oxazolomycin biosynthetic pathway,is indeed diverting a portion of the glycolytic intermediate into the biosynthesis of polyketides,such as oxazolomycin and tautomycin.It is demonstrated that OzmB first sequesters D-l,3-bisphosphoglycerate from the glycolytic pool to form the D-3-phosphoglyceryl-S-OzmB intermediate,then removes the phosphate group to afford the D-3-glyceryl-S-OzmB species (acting as a phosphatase),and finally transfers the glyceryl group to an acyl carrier protein (ACP) to set the stage for polyketide biosynthesis (acting as a glyceryl trans-ferase) (Figure 1).Each of the steps catalyzed by OzmB was monitored using nanospray Fourier transform ion cyclotron resonance mass spectrometry (nFT-ICRMS).