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Applied and Environmental Microbiology, November 2005, p. 6977-6985, Vol. 71, No. 11
0099-2240/05/$08.00+0     doi:10.1128/AEM.71.11.6977-6985.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.

Biocatalytic Conversion of Avermectin to 4"-Oxo-Avermectin: Heterologous Expression of the ema1 Cytochrome P450 Monooxygenase

István Molnár,^1* D. Steven Hill,^1, Ross Zirkle,^1, Philip E. Hammer,^1, Frank Gross,^1,¶ Thomas G. Buckel,^2,|| Volker Jungmann,^2* Johannes Paul Pachlatko,^2, and James M. Ligon^1,

Syngenta Biotechnology, Inc., 3054 Cornwallis Rd., Research Triangle Park, NC 27709,¹ Syngenta Crop Protection AG, Schwarzwaldallee 215, CH-4002 Basel, Switzerland²

Received 3 February 2005/ Accepted 15 July 2005

The cytochrome P450 monooxygenase Ema1 from Streptomyces tubercidicus R-922 and its homologs from closely related Streptomyces strains are able to catalyze the regioselective oxidation of avermectin into 4"-oxo-avermectin, a key intermediate in the manufacture of the agriculturally important insecticide emamectin benzoate (V. Jungmann, I. Molnár, P. E. Hammer, D. S. Hill, R. Zirkle, T. G. Buckel, D. Buckel, J. M. Ligon, and J. P. Pachlatko, Appl. Environ. Microbiol. 71:6968-6976, 2005). The gene for Ema1 has been expressed in Streptomyces lividans, Streptomyces avermitilis, and solvent-tolerant Pseudomonas putida strains using different promoters and vectors to provide biocatalytically competent cells. Replacing the extremely rare TTA codon with the more frequent CTG codon to encode Leu4 in Ema1 increased the biocatalytic activities of S. lividans strains producing this enzyme. Ferredoxins and ferredoxin reductases were also cloned from Streptomyces coelicolor and biocatalytic Streptomyces strains and tested in ema1 coexpression systems to optimize the electron transport towards Ema1.

Present address: BASF Agricultural Products, 26 Davis Dr., Research Triangle Park, NC 27709.

Present address: Martek Biosciences, 4909 Nautilus Ct. North, Boulder, CO 80301.

Present address: Athenix Corp., 2202 Ellis Rd., Suite B, Durham, NC 27702.

^¶ Present address: Gene Bridges GmbH, Tatzberg 47-51, 01307 Dresden, Germany.

^|| Present address: F. Hoffmann-La Roche, Ltd., Grenzacherstrasse 124, CH-4070 Basel, Switzerland.

Present address: Bölchenstrasse 21, CH-4411 Seltisberg, Switzerland.

This article has been cited by other articles:

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