tailieunhanh - Báo cáo khoa học: Structural basis for the erythro-stereospecificity of the L-arginine oxygenase VioC in viomycin biosynthesis

The nonheme iron oxygenase VioC fromStreptomyces vinaceuscatalyzes Fe(II)-dependent and a-ketoglutarate-dependent Cb-hydroxylation of l-arginine during the biosynthesis of the tuberactinomycin antibiotic vio-mycin. Crystal structures of VioC were determined in complexes with the cofactor Fe(II), the substrate l-arginine, the product (2S,3S)-hydroxyargi-nine and the coproduct succinate at – A˚ resolution. | ỊFEBS Journal Structural basis for the erythro-stereospecificity of the L-arginine oxygenase VioC in viomycin biosynthesis Verena Helmetag1 Stefan A. Samel1 Michael G. Thomas2 Mohamed A. Marahiel1 and Lars-Oliver Essen1 1 Biochemistry Department of Chemistry Philipps-University Marburg Germany 2 Department of Bacteriology University of Wisconsin-Madison WI USA Keywords Cp-hydroxylation of L-arginine iron II a-ketoglutarate-dependent oxygenase nonribosomal peptide synthesis oxidoreductase viomycin Correspondence . Essen and M. A. Marahiel Biochemistry Department of Chemistry Philipps-University Marburg Hans-Meerwein-Strasse D-35032 Marburg Germany Fax 49 0 6421 28 22012 Tel 49 0 6421 28 22032 E-mail essen@ marahiel@ Received 31 March 2009 revised 30 April 2009 accepted 5 May 2009 doi The nonheme iron oxygenase VioC from Streptomyces vinaceus catalyzes Fe II -dependent and a-ketoglutarate-dependent cp-hydroxylation of L-arginine during the biosynthesis of the tuberactinomycin antibiotic vio-mycin. Crystal structures of VioC were determined in complexes with the cofactor Fe II the substrate L-arginine the product 2S 3S -hydroxyargi-nine and the coproduct succinate at JI resolution. The overall structure reveals a p-helix core fold with two additional helical subdomains that are common to nonheme iron oxygenases of the clavaminic acid synthase-like superfamily. In contrast to other clavaminic acid synthase-like oxygenases which catalyze the formation of threo diastereomers VioC produces the erythro diastereomer of cp-hydroxylated L-arginine. This unexpected stereospecificity is caused by conformational control of the bound substrate which enforces a gauche - conformer for v1 instead of the trans conformers observed for the asparagine oxygenase AsnO and other members of the clavaminic acid synthase-like superfamily. Additionally the substrate specificity of VioC was investigated. The .