Crystal structure of 2-nitropropane dioxygenase complexed with FMN and substrate. Identification of the catalytic base.
Nitroalkane compounds are widely used in chemical industry and are also produced by microorganisms and plants. Some nitroalkanes have been demonstrated to be carcinogenic, and enzymatic oxidation of nitroalkanes is of considerable interest. 2-Nitropropane dioxygenases from Neurospora crassa and Williopsis mrakii (Hansenula mrakii), members of one family of the nitroalkane-oxidizing enzymes, contain FMN and FAD, respectively. The enzymatic oxidation of nitroalkanes by 2-nitropropane dioxygenase operates by an oxidase-style catalytic mechanism, which was recently shown to involve the formation of an anionic flavin semiquinone. This represents a unique case in which an anionic flavin semiquinone has been experimentally observed in the catalytic pathway for oxidation catalyzed by a flavin-dependent enzyme. Here we report the first crystal structure of 2-nitropropane dioxygenase from Pseudomonas aeruginosa in two forms: a binary complex with FMN and a ternary complex with both FMN and 2-nitropropane. The structure identifies His(152) as the proposed catalytic base, thus providing a structural framework for a better understanding of the catalytic mechanism.
Ha
Jun Yong
JY
Department of Chemistry, College of Natural Sciences, Seoul National University, Seoul 151-742, Korea.
Min
Ji Young
JY
Lee
Su Kyung
SK
Kim
Hyoun Sook
HS
Kim
Do Jin
DJ
Kim
Kyoung Hoon
KH
Lee
Hyung Ho
HH
Kim
Hye Kyung
HK
Yoon
Hye-Jin
HJ
Suh
Se Won
SW