Publications

• In vitro reconstitution of EryCIII activity for the preparation of unnatural macrolides.

  Yuan Y., Chung H.S., Leimkuhler C., Walsh C.T., Kahne D., Walker S.

  EryCIII is a desosaminyltransferase that converts an inactive macrolide precursor to a biologically active antibiotic. It may have potential for the synthesis of unnatural macrolides with useful biological activities. However, it has been difficult to reconstitute the activity of EryCIII in vitro. ... >> More

  EryCIII is a desosaminyltransferase that converts an inactive macrolide precursor to a biologically active antibiotic. It may have potential for the synthesis of unnatural macrolides with useful biological activities. However, it has been difficult to reconstitute the activity of EryCIII in vitro. We report here that purified, inactive EryCIII can be converted to an active catalyst by the addition of another protein encoded in the same gene cluster, EryCII. The EryCII-treated protein retains activity even when EryCII is removed. We also show that AknT, an activator protein from an unrelated gene cluster, is capable of activating EryCIII. Although the mechanism of activation is not yet understood, we have concluded from these experiments that these antibiotic Gtf activator proteins do not function to deliver substrates to EryCIII and do not exert their effects by forming stable complexes with the Gtf during the glycosyltransfer reaction. We report that activated EryCIII is capable of utilizing an alternative sugar donor, so these results lay the groundwork for the production of novel macrolides. << Less

  J. Am. Chem. Soc. 127:14128-14129(2005) [PubMed] [EuropePMC]

• Reconstitution and characterization of a new desosaminyl transferase, EryCIII, from the erythromycin biosynthetic pathway.

  Lee H.Y., Chung H.S., Hang C., Khosla C., Walsh C.T., Kahne D., Walker S.

  EryCIII converts alpha-mycarosyl erythronolide B into erythromycin D using TDP-d-desosamine as the glycosyl donor. We report the heterologous expression, purification, in vitro reconstitution, and preliminary characterization of EryCIII. Coexpression of EryCIII with the GroEL/ES chaperone complex ... >> More

  EryCIII converts alpha-mycarosyl erythronolide B into erythromycin D using TDP-d-desosamine as the glycosyl donor. We report the heterologous expression, purification, in vitro reconstitution, and preliminary characterization of EryCIII. Coexpression of EryCIII with the GroEL/ES chaperone complex was found to enhance greatly the expression of soluble EryCIII protein. The enzyme was found to be highly active with a kcat greater than 100 min-1. EryCIII was quite selective for the natural nucleotide sugar donor and macrolide acceptor substrates, unlike several other antibiotic glycosyl transferases with broad specificity such as desVII, oleG2, and UrdGT2. Within detectable limits, neither 6-deoxyerythronolide B nor 10-deoxymethynolide were found to be glycosylated by EryCIII. Furthermore, TDP-d-mycaminose, which only differs from TDP-d-desosamine at the C4 position, could not be transferred to alphaMEB. These studies lay the groundwork for detailed structural and mechanistic analysis of an important member of the desosaminyl transferase family of enzymes. << Less

  J. Am. Chem. Soc. 126:9924-9925(2004) [PubMed] [EuropePMC]