title: Crystal structure of halogenase PltA from the pyoluteorin biosynthetic pathway.
abstract: Pyoluteorin is an antifungal agent composed of a 4,5-dichlorinated pyrrole group linked to a resorcinol moiety. The pyoluteorin biosynthetic gene cluster in Pseudomonas fluorescens Pf-5 encodes the halogenase PltA, which has been previously demonstrated to perform both chlorinations in vitro. PltA selectively accepts as a substrate a pyrrole moiety covalently tethered to a nonribosomal peptide thiolation domain PltL (pyrrolyl-S-PltL) for FAD-dependent di-chlorination, yielding 4,5-dichloropyrrolyl-S-PltL. We report a 2.75 Å-resolution crystal structure of PltA in complex with FAD and chloride. PltA is a dimeric enzyme, containing a flavin-binding fold conserved in flavin-dependent halogenases and monooxygenases, and an additional unique helical region at the C-terminus. This C-terminal region blocks a putative substrate-binding cleft, suggesting that a conformational change involving repositioning of this region is necessary to allow binding of the pyrrolyl-S-PltL substrate for its dichlorination by PltA.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536-0596, USA.
authors.forename: Allan H
authors.initials: AH
authors.lastname: Pang
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536-0596, USA.
authors.forename: Sylvie
authors.initials: S
authors.lastname: Garneau-Tsodikova
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536-0596, USA. Electronic address: oleg.tsodikov@uky.edu.
authors.forename: Oleg V
authors.initials: OV
authors.lastname: Tsodikov
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000648:ultrastructure*; D001665:Binding Sites; D002713:Chlorine / Q000737:chemistry*; D018360:Crystallography, X-Ray; D005182:Flavin-Adenine Dinucleotide / Q000737:chemistry*; D054879:Halogenation / Q000502:physiology*; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry; D010636:Phenols / Q000737:chemistry*; D011485:Protein Binding / Q000502:physiology; D011551:Pseudomonas fluorescens / Q000378:metabolism; D011758:Pyrroles / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D010636:Phenols; D011758:Pyrroles; C095503:pyoluteorin; D005182:Flavin-Adenine Dinucleotide; D002713:Chlorine; D010088:Oxidoreductases
keywords: Chlorination; FAD; Flavoprotein; Halogenation; Natural product