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Angew Chem Int Ed Engl. 2016 May 4;55(19):5780-4. doi: 10.1002/anie.201601447. Epub 2016 Mar 30.

Discovery of a Promiscuous Non-Heme Iron Halogenase in Ambiguine Alkaloid Biogenesis: Implication for an Evolvable Enzyme Family for Late-Stage Halogenation of Aliphatic Carbons in Small Molecules.

Author information

1
Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA.
2
Department of Chemistry, University of Pittsburgh, 219 Parkman Avenue, Pittsburgh, PA, 15260, USA. xinyuliu@pitt.edu.

Abstract

The elucidation of enigmatic enzymatic chlorination timing in ambiguine indole alkaloid biogenesis led to the discovery and characterization of AmbO5 protein as a promiscuous non-heme iron aliphatic halogenase. AmbO5 was shown capable of selectively modifying seven structurally distinct ambiguine, fischerindole and hapalindole alkaloids with chlorine via late-stage aliphatic C-H group functionalization. Cross-comparison of AmbO5 with a previously characterized aliphatic halogenase homolog WelO5 that has a restricted substrate scope led to the identification of a C-terminal sequence motif important for substrate tolerance and specificity. Mutagenesis of 18 residues of WelO5 within the identified sequence motif led to a functional mutant with an expanded substrate scope identical to AmbO5, but an altered substrate specificity from the wild-type enzymes. These observations collectively provide evidence on the evolvable nature of AmbO5/WelO5 enzyme duo in the context of hapalindole-type alkaloid biogenesis and implicate their promise for the future development of designer biocatalysis for the selective late-stage modification of unactivated aliphatic carbon centers in small molecules with halogens.

KEYWORDS:

C−H activation; alkaloid biogenesis; evolution; halogenase; non-heme iron enzyme

PMID:
27027281
DOI:
10.1002/anie.201601447
[Indexed for MEDLINE]

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