Studies on the mechanism of chain release in the biosynthesis of the polyether antibiotic nanchangmycin

BIOL 247

Tiangang Liu, Department of Chemistry and Department of Molecular Biology, Brown University and Shanghai Jiaotong Univerisity, BoxH, 324 Brook Street, Providence, RI 02912, Zixin Deng, zxdeng@sjtu.edu.cn, Laboratory of Microbial Metabolism and School of Life Science& Biotechnology, Shanghai Jiaotong University, Huashan Road 1954, Science building 3rd Floor, Shanghai, 200030, China, and David E. Cane, david_cane@brown.edu, Department of Chemistry, Brown University, 324 Brook Street, Providence, RI 02912.
Modular polyketide synthases are multienzyme synthases responsible for the biosynthesis of many important macrolide antibiotics. The last step in this biosynthesis is usually the chain release from a carrier protein by a thioesterase domain. However, the polyketide synthase system responsible for the biosynthesis of the polyether antibiotic nanchangmycin lacks an apparent thioesterase enzyme. We have identified NanE as a novel standalone thioesterase whose role is specifically the polyether chain release from the acyl-carrier protein. A series of polyether-N-acetylcysteamine (SNAC) thioesters have been tested as substrates for kinetic analysis with this new enzyme in order to study its possible broad specificity. Site-directed mutagenesis of NanE has also been performed to identify the catalytic triad of this enzyme, and the specific Ser, Asp, and His mutants all have lost their hydrolytic activity towards the substrates used.

 

Frontiers in Chemical Biology
5:00 PM-7:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster

Division of Biological Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007