2ar8 | pdb_00002ar8

The structure of tryptophan 7-halogenase (PrnA)suggests a mechanism for regioselective chlorination

File:2ar8.gif

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2ar8, resolution 2.200Å
Ligands:	CL, CTE and FAD
Gene:	PrnA (Pseudomonas fluorescens)
Coordinates:	save as pdb, mmCIF, xml

Overview

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.

About this Structure

2AR8 is a Single protein structure of sequence from Pseudomonas fluorescens. Full crystallographic information is available from OCA.

Reference

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

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