title: Three-dimensional structure of AzoR from Escherichia coli. An oxidereductase conserved in microorganisms.
abstract: The crystal structure of AzoR (azoreductase) has been determined in complex with FMN for two different crystal forms at 1.8 and 2.2 A resolution. AzoR is an oxidoreductase isolated from Escherichia coli as a protein responsible for the degradation of azo compounds. This enzyme is an FMN-dependent NADH-azoreductase and catalyzes the reductive cleavage of azo groups by a ping-pong mechanism. The structure suggests that AzoR acts in a homodimeric state forming the two identical catalytic sites to which both monomers contribute. The structure revealed that each monomer of AzoR has a flavodoxin-like structure, without the explicit overall amino acid sequence homology. Superposition of the structures from the two different crystal forms revealed the conformational change and suggested a mechanism for accommodating substrates of different size. Furthermore, comparison of the active site structure with that of NQO1 complexed with substrates provides clues to the possible substrate-binding mechanism of AzoR.
authors: Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors: Kosuke
authors: K
authors: Ito
authors: Masayuki
authors: M
authors: Nakanishi
authors: Woo-Cheol
authors: WC
authors: Lee
authors: Hiroshi
authors: H
authors: Sasaki
authors: Shuhei
authors: S
authors: Zenno
authors: Kaoru
authors: K
authors: Saigo
authors: Yukio
authors: Y
authors: Kitade
authors: Masaru
authors: M
authors: Tanokura