Mechanistic studies of DpgC, a unique dioxygenase in vancomycin biosynthesis

BIOL 222

Elisha N Fielding, fieldiel@bc.edu, Paul F. Widboom, widboom@bc.edu, Ye Liu, and Steve D. Bruner. Department of Chemistry, Boston College, 5 Beals St, Apt 1, Brookline, MA 02446
DpgC is a unique dioxygenase found in the vancomycin biosynthesic pathway that catalyzes the oxidation of 3,5-dihydroxylphenylacetyl-CoA (DPA-CoA) to 3,5-dihydroxyphenylglyoxylate (Dpg) independent of metals or cofactors. Recently, the structure of DpgC with a bound substrate mimic has been solved and a mechanism proposed. Here, we describe the use of available structural information to design mutations and substrate analogs to further probe this unusual reaction. Biochemical assays of active site point mutants (Glu189Gln, Arg254Lys, Glu255Gln, Glu299Asn) predicted to be important for the recognition and chemistry of DPA-CoA were performed. In addition, substrate analogs (3-hydroxyphenylacetyl-CoA, 4-hydroxyphenylacetyl-CoA, phenylacetyl-CoA) were synthesized and kinetically evaluated. The results show that DpgC uses novel modes of substrate recognition to perform the unique chemistry catalyzed by this cofactor independent dioxygenase.

 

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