Crystallographic trapping in the rebeccamycin biosynthetic enzyme RebC
- 25 September 2007
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 104 (39), 15311-15316
- https://doi.org/10.1073/pnas.0707190104
Abstract
The biosynthesis of rebeccamycin, an antitumor compound, involves the remarkable eight-electron oxidation of chlorinated chromopyrrolic acid. Although one rebeccamycin biosynthetic enzyme is capable of generating low levels of the eight-electron oxidation product on its own, a second protein, RebC, is required to accelerate product formation and eliminate side reactions. However, the mode of action of RebC was largely unknown. Using crystallography, we have determined a likely function for RebC as a flavin hydroxylase, captured two snapshots of its dynamic catalytic cycle, and trapped a reactive molecule, a putative substrate, in its binding pocket. These studies strongly suggest that the role of RebC is to sequester a reactive intermediate produced by its partner protein and to react with it enzymatically, preventing its conversion to a suite of degradation products that includes, at low levels, the desired product.Keywords
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