An Unusual Role for a Mobile Flavin in StaC-like Indolocarbazole Biosynthetic Enzymes
Author(s)Goldman, Peter J.; Ryan, Katherine S.; Hamill, Michael J.; Howard-Jones, Annaleise R.; Walsh, Christopher T.; Elliott, Sean J.; Drennan, Catherine L.; Ryan, Katherine S.; ... Show more Show less
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The indolocarbazole biosynthetic enzymes StaC, InkE, RebC, and AtmC mediate the degree of oxidation of chromopyrrolic acid on route to the natural products staurosporine, K252a, rebeccamycin, and AT2433-A1, respectively. Here, we show that StaC and InkE, which mediate a net 4-electron oxidation, bind FAD with a micromolar Kd, whereas RebC and AtmC, which mediate a net 8-electron oxidation, bind FAD with a nanomolar Kd while displaying the same FAD redox properties. We further create RebC-10x, a RebC protein with ten StaC-like amino acid substitutions outside of previously characterized FAD-binding motifs and the complementary StaC-10x. We find that these mutations mediate both FAD affinity and product specificity, with RebC-10x displaying higher StaC activity than StaC itself. X-ray structures of this StaC catalyst identify the substrate of StaC as 7-carboxy-K252c and suggest a unique mechanism for this FAD-dependent enzyme.
DepartmentMassachusetts Institute of Technology. Department of Biology; Massachusetts Institute of Technology. Department of Chemistry
Chemistry & Biology
Springer Science + Business Media B.V.
Goldman, Peter J., Katherine S. Ryan, Michael J. Hamill, Annaleise R. Howard-Jones, Christopher T. Walsh, Sean J. Elliott, and Catherine L. Drennan. “An Unusual Role for a Mobile Flavin in StaC-like Indolocarbazole Biosynthetic Enzymes.” Chemistry & Biology 19, no. 7 (July 2012): 855-865.
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