Publication Abstract from PubMed
Chlorinated natural products include vancomycin and cryptophycin A. Their biosynthesis involves regioselective chlorination by flavin-dependent halogenases. We report the structural characterization of tryptophan 7-halogenase (PrnA), which regioselectively chlorinates tryptophan. Tryptophan and flavin adenine dinucleotide (FAD) are separated by a 10 angstrom-long tunnel and bound by distinct enzyme modules. The FAD module is conserved in halogenases and is related to flavin-dependent monooxygenases. On the basis of biochemical studies, crystal structures, and by analogy with monooxygenases, we predict that FADH2 reacts with O2 to make peroxyflavin, which is decomposed by Cl-. The resulting HOCl is guided through the tunnel to tryptophan, where it is activated to participate in electrophilic aromatic substitution.
Tryptophan 7-halogenase (PrnA) structure suggests a mechanism for regioselective chlorination.,Dong C, Flecks S, Unversucht S, Haupt C, van Pee KH, Naismith JH Science. 2005 Sep 30;309(5744):2216-9. PMID:16195462[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
