BIOL 246 |
| PikC is the cytochrome P450 catalyzing the final hydroxylation step in the biosynthesis of antibiotics pikromycin/methymycin in Streptomyce venezuelae. This biosynthetic enzyme has shown remarkable substrate flexibility and product diversity. Specifically, PikC is able to hydroxylate two physiological substrates 12-membered (YC-17) or 14-membered (narbomycin) ring macrolide at various position(s), leading to a series of macrolide antibiotics. Recently, we resolved the x-ray crystal structures of PikC in both substrate-free and -bound forms. Together with site-directed mutagenesis and substrate binding affinity measurements, the first insight into the structural basis for the unique hydroxylation patterns was provided. Two different binding pockets for YC-17 and narbomycin respectively were identified. The interactions between specific amino acids in the BC-loop region of this P450 and the deoxysugar C3' dimethylamino group through salt bridge and hydrogen bond were proved to be critical for the substrate binding and functionality of PikC. We also revealed this late stage P450-tailoring improved the biological activities of these antibiotics. Therefore, on the basis of the more in-depth understanding of PikC in substrate flexibility and functionality, the structure-guided design of a PikC-like enzyme could generate a novel biocatalyst, which can be used to develop novel antibiotics with higher potency or new action mode to fight against the stubborn drug-resistant pathogens. |
|
Frontiers in Chemical Biology
5:00 PM-7:00 PM, Wednesday, August 22, 2007 BCEC -- Exhibit Hall - B2, Poster
Division of Biological Chemistry |