title: Insight into the structure-function relationship of the nonheme iron halogenases involved in the biosynthesis of 4-chlorothreonine --Thr3 from Streptomyces sp. OH-5093 and SyrB2 from Pseudomonas syringae pv. syringae B301DR.
abstract: Molecular cloning of the biosynthetic gene cluster involved in the production of free 4-chlorothreonine in Streptomyces sp. OH-5093 showed the presence of six ORFs: thr1, thr2, thr3, orf1, orf2 and thr4. According to bioinformatic analysis, thr1, thr2, thr3 and thr4 encode a free-standing adenylation domain, a carrier protein, an Fe(II) nonheme α-ketoglutarate-dependent halogenase and a thioesterase, respectively, indicating the role of these genes in the activation and halogenation of threonine and the release of 4-chlorothreonine in a pathway closely reflecting the formation of this amino acid in the biosynthesis of the lipodepsipeptide syringomycin from Pseudomonas syringae pv. syringae B301DR. Orf1 and orf2 show sequence similarity with alanyl/threonyl-tRNA synthetases editing domains and drug metabolite transporters, respectively. We show that thr3 can replace the halogenase gene syrB2 in the biosynthesis of syringomycin, by functional complementation of the mutant P. s. pv. syringae strain BR135A1 inactivated in syrB2. We also provide an insight into the structure-function relationship of halogenases Thr3 and SyrB2 using homology modelling and site-directed mutagenesis.
authors.affiliation: Department of Biochemical Sciences A. Rossi Fanelli, Sapienza University of Rome, Rome, Italy.
authors.forename: Maria Rosaria
authors.initials: MR
authors.lastname: Fullone
authors.forename: Alessandro
authors.initials: A
authors.lastname: Paiardini
authors.forename: Rossella
authors.initials: R
authors.lastname: Miele
authors.forename: Sara
authors.initials: S
authors.lastname: Marsango
authors.forename: Dennis C
authors.initials: DC
authors.lastname: Gross
authors.forename: Satoshi
authors.initials: S
authors.lastname: Omura
authors.forename: Enric
authors.initials: E
authors.lastname: Ros-Herrera
authors.forename: Maria Carmela
authors.initials: MC
authors.lastname: Bonaccorsi di Patti
authors.forename: Aldo
authors.initials: A
authors.lastname: Laganà
authors.forename: Stefano
authors.initials: S
authors.lastname: Pascarella
authors.forename: Ingeborg
authors.initials: I
authors.lastname: Grgurina
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019295:Computational Biology; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D044224:Pseudomonas syringae / Q000201:enzymology*; D013302:Streptomyces / Q000201:enzymology*; D013329:Structure-Activity Relationship; D013912:Threonine / Q000031:analogs & derivatives* / Q000096:biosynthesis
chemical_list: D001426:Bacterial Proteins; C032677:syringomycin; C090484:4-chlorothreonine; D013912:Threonine