View the Current Issue

Article

  • The EMBO Journal (2003) 22, 205 - 215
  • doi:10.1093/emboj/cdg031

The structure of ActVA-Orf6, a novel type of monooxygenase involved in actinorhodin biosynthesis

Giuliano Sciara1, Steven G. Kendrew1,2, Adriana E. Miele1, Neil G. Marsh3, Luca Federici1, Francesco Malatesta4, Giuliana Schimperna5, Carmelinda Savino6 and Beatrice Vallone1

  1. Dipartimento di Scienze Biochimiche Università di Roma 'La Sapienza', Piazzale A.Moro 5, 00185 Roma, Italy
  2. Biotica Technology Ltd, 181A Huntingdon Road, Cambridge CB3 0DJ, UK
  3. Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA
  4. Dipartimento di Biologia di Base ed Applicata, Università di L'Aquila, 67100 L'Aquila Italy
  5. Istituto G.Donegani, 28100 Novara, Italy
  6. CNR, Centro di Studi sulla Biologia Molecolare, c/o Dipartimento di Scienze Biochimiche, Università di Roma 'La Sapienza', Piazzale A.Moro, 5, 00185 Roma, Italy

Correspondence to:

Beatrice Vallone, E-mail: beatrice.vallone@uniroma1.it

Received 9 August 2002; Accepted 19 November 2002; Revised 13 November 2002

ActVA-Orf6 monooxygenase from Streptomyces coelicolor that catalyses the oxidation of an aromatic intermediate of the actinorhodin biosynthetic pathway is a member of a class of small monooxygenases that carry out oxygenation without the assistance of any of the prosthetic groups, metal ions or cofactors normally associated with activation of molecular oxygen. The overall structure is a ferredoxin-like fold with a novel dimeric assembly, indicating that the widely represented ferredoxin fold may sustain yet another functionality. The resolution (1.3 Å) of the enzyme structure and its complex with substrate and product analogues allows us to visualize the mechanism of binding and activation of the substrate for attack by molecular oxygen, and utilization of two gates for the reaction components including a proton gate and an O2/H2O gate with a putative protein channel. This is the first crystal structure of an enzyme involved in the tailoring of a type II aromatic polyketide and illustrates some of the enzyme–substrate recognition features that may apply to a range of other enzymes involved in modifying a polyketide core structure.

  • Keywords:

    • actinorhodin,
    • monooxygenase,
    • polyketide,
    • protein structure,
    • Streptomyces coelicolor