Science 2001-01-12

A role for flavin monooxygenase-like enzymes in auxin biosynthesis.

Y Zhao, S K Christensen, C Fankhauser, J R Cashman, J D Cohen, D Weigel, J Chory

Index: Science 291(5502) , 306-9, (2001)

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Abstract

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.