Affiliation:
1. Life Sciences Institute University of Michigan Ann Arbor MÌ 48109 USA
2. Department of Chemistry and Biochemistry University of California Los Angeles Los Angeles CA USA
3. Department of Chemistry Massachusetts Institute of Technology Cambridge MA 02139 USA
Abstract
AbstractIn the biosynthesis of the tryptophan‐linked dimeric diketopiperazines (DKPs), cytochromes P450 selectively couple DKP monomers to generate a variety of intricate and isomeric frameworks. To determine the molecular basis for selectivity of these biocatalysts we obtained a high‐resolution crystal structure of selective Csp2−N bond forming dimerase, AspB. Overlay of the AspB structure onto C−C and C−N bond forming homolog NzeB revealed no significant structural variance to explain their divergent chemoselectivities. Molecular dynamics (MD) simulations identified a region of NzeB with increased conformational flexibility relative to AspB, and interchange of this region along with a single active site mutation led to a variant that catalyzes exclusive C−N bond formation. MD simulations also suggest that intermolecular C−C or C−N bond formation results from a change in mechanism, supported experimentally through use of a substrate mimic.
Funder
National Science Foundation
National Institute of General Medical Sciences