Crystal Structure of Dicamba Monooxygenase: A Rieske Nonheme Oxygenase that Catalyzes Oxidative Demethylation

Razvan Dumitru, Wen Zhi Jiang, Donald P. Weeks, Mark A. Wilson

Research output: Contribution to journalArticle

33 Scopus citations


Dicamba (3,6-dichloro-2-methoxybenzoic acid) is a widely used herbicide that is efficiently degraded by soil microbes. These microbes use a novel Rieske nonheme oxygenase, dicamba monooxygenase (DMO), to catalyze the oxidative demethylation of dicamba to 3,6-dichlorosalicylic acid (DCSA) and formaldehyde. We have determined the crystal structures of DMO in the free state, bound to its substrate dicamba, and bound to the product DCSA at 2.10-1.75 Å resolution. The structures show that the DMO active site uses a combination of extensive hydrogen bonding and steric interactions to correctly orient chlorinated, ortho-substituted benzoic-acid-like substrates for catalysis. Unlike other Rieske aromatic oxygenases, DMO oxygenates the exocyclic methyl group, rather than the aromatic ring, of its substrate. This first crystal structure of a Rieske demethylase shows that the Rieske oxygenase structural scaffold can be co-opted to perform varied types of reactions on xenobiotic substrates.

Original languageEnglish (US)
Pages (from-to)498-510
Number of pages13
JournalJournal of Molecular Biology
Issue number2
Publication statusPublished - Sep 18 2009



  • Rieske protein
  • X-ray crystallography
  • nonheme oxygenase
  • protein structure
  • xenobiotic degradation

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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