title: Nitration of a peptide phytotoxin by bacterial nitric oxide synthase.
abstract: Nitric oxide (NO) is a potent intercellular signal in mammals that mediates key aspects of blood pressure, hormone release, nerve transmission and the immune response of higher organisms. Proteins homologous to full-length mammalian nitric oxide synthases (NOSs) are found in lower multicellular organisms. Recently, genome sequencing has shown that some bacteria contain genes coding for truncated NOS proteins; this is consistent with reports of NOS-like activities in bacterial extracts. Biological functions for bacterial NOSs are unknown, but have been presumed to be analogous to their role in mammals. Here we describe a gene in the plant pathogen Streptomyces turgidiscabies that encodes a NOS homologue, and we reveal its role in nitrating a dipeptide phytotoxin required for plant pathogenicity. High similarity between bacterial NOSs indicates a general function in biosynthetic nitration; thus, bacterial NOSs constitute a new class of enzymes. Here we show that the primary function of Streptomyces NOS is radically different from that of mammalian NOS. Surprisingly, mammalian NO signalling and bacterial biosynthetic nitration share an evolutionary origin.
authors.affiliation: Department of Plant Pathology, Cornell University, Ithaca, New York 14853, USA.
authors.forename: Johan A
authors.initials: JA
authors.lastname: Kers
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wach
authors.forename: Stuart B
authors.initials: SB
authors.lastname: Krasnoff
authors.forename: Joanne
authors.initials: J
authors.lastname: Widom
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Cameron
authors.forename: Raghida A
authors.initials: RA
authors.lastname: Bukhalid
authors.forename: Donna M
authors.initials: DM
authors.lastname: Gibson
authors.forename: Brian R
authors.initials: BR
authors.lastname: Crane
authors.forename: Rosemary
authors.initials: R
authors.lastname: Loria
mesh_terms: D001120:Arginine / Q000031:analogs & derivatives* / Q000378:metabolism; D017353:Gene Deletion; D005798:Genes, Bacterial / Q000235:genetics; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D009566:Nitrates / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D010879:Piperazines / Q000737:chemistry / Q000378:metabolism*; D010944:Plants / Q000187:drug effects; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics; D014118:Toxins, Biological / Q000737:chemistry / Q000378:metabolism
chemical_list: D007211:Indoles; D009566:Nitrates; D009573:Nitrites; D010879:Piperazines; D014118:Toxins, Biological; C406691:thaxtomine A; C068309:N(omega)-hydroxyarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D009584:Nitrogen