A role for flavin monooxygenase-like enzymes in auxin biosynthesis.
Although auxin is known to regulate many processes in plant development and has been studied for over a century, the mechanisms whereby plants produce it have remained elusive. Here we report the characterization of a dominant Arabidopsis mutant, yucca, which contains elevated levels of free auxin. YUCCA encodes a flavin monooxygenase-like enzyme and belongs to a family that includes at least nine other homologous Arabidopsis genes, a subset of which appears to have redundant functions. Results from tryptophan analog feeding experiments and biochemical assays indicate that YUCCA catalyzes hydroxylation of the amino group of tryptamine, a rate-limiting step in tryptophan-dependent auxin biosynthesis.
Zhao
Y
Y
Howard Hughes Medical Institute, Plant Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, CA 92037, USA.
Christensen
S K
SK
Fankhauser
C
C
Cashman
J R
JR
Cohen
J D
JD
Weigel
D
D
Chory
J
J
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins; D002384:Catalysis; D003001:Cloning, Molecular; D017343:Genes, Plant; D007210:Indoleacetic Acids / Q000096:biosynthesis* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010084:Oxidation-Reduction; D010105:Oxygenases / Q000737:chemistry / Q000378:metabolism*; D010641:Phenotype; D018517:Plant Roots / Q000254:growth & development; D010947:Plants, Toxic; D014026:Nicotiana / Q000378:metabolism; D014363:Tryptamines / Q000378:metabolism; D014364:Tryptophan / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology
D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D014363:Tryptamines; C004182:5-methyltryptophan; C030820:tryptamine; D014364:Tryptophan; D010105:Oxygenases; C422746:YUC protein, Arabidopsis