title: IAA-synthase, an enzyme complex from Arabidopsis thaliana catalyzing the formation of indole-3-acetic acid from (S)-tryptophan.
abstract: An enzyme complex was isolated from Arabidopsis thaliana that catalyzes the entire pathway of biosynthesis of the major plant growth hormone, indole-3-acetic acid (IAA), from (S)-tryptophan. The 160-180 kDa, soluble complex catalyzes a strictly O2-dependent reaction which requires no further added factors and is stereospecific for the substrate (S)-tryptophan (app. Km = 120 microM). H2(18)O labeling proved that both oxygen atoms of IAA were delivered via H2O. This, as well as immunological evidence for the presence of a nitrilase-like protein in the complex, suggests the reaction to proceed via the intermediate indole-3-acetonitrile. IAA-synthase forms a tight metabolite channel committed to IAA production and occurs in shoots, roots and cell cultures of A. thaliana.
authors.affiliation: Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität Bochum, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Müller
authors.forename: E W
authors.initials: EW
authors.lastname: Weiler
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000378:metabolism; D008401:Gas Chromatography-Mass Spectrometry; D007210:Indoleacetic Acids / Q000378:metabolism*; D007700:Kinetics; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000302:isolation & purification* / Q000378:metabolism* / Q000502:physiology; D010100:Oxygen / Q000378:metabolism; D010936:Plant Extracts / Q000378:metabolism; D010937:Plant Growth Regulators / Q000096:biosynthesis* / Q000378:metabolism; D012966:Sodium Cyanide / Q000494:pharmacology; D013237:Stereoisomerism; D014364:Tryptophan / Q000378:metabolism*; D014867:Water / Q000378:metabolism
chemical_list: D007210:Indoleacetic Acids; D009097:Multienzyme Complexes; D010936:Plant Extracts; D010937:Plant Growth Regulators; C421912:indole-3-acetic acid synthase; D014867:Water; C030737:indoleacetic acid; D014364:Tryptophan; D012966:Sodium Cyanide; D010100:Oxygen