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- Title
Channeling and conformational changes in the heterotetrameric sarcosine oxidase from Corynebacterium sp. U-96.
- Authors
Moriguchi, Tomotaka; Ida, Koh; Hikima, Takaaki; Ueno, Go; Yamamoto, Masaki; Suzuki, Haruo
- Abstract
We characterized the crystal structures of heterotetrameric sarcosine oxidase (SO) from Corynebacterium sp. U-96 complexed with methylthioacetate (MTA), pyrrole 2-carboxylate (PCA) and sulphite, and of sarcosine-reduced SO. SO comprises α-, β-, γ- and δ-subunits; FAD and FMN cofactors; and a large internal cavity. MTA and PCA are sandwiched between the re-face of the FAD isoalloxazine ring and the β-subunit C-terminal residues. Reduction of flavin cofactors shifts the β-subunit Ala1 towards the α-subunit Met55, forming a surface cavity at the oxygen-channel vestibule and rendering the β-subunit C-terminal residues mobile. We identified three channels connecting the cavity and the enzyme surface. Two of them exist in the inter-subunit space between α and β-subunits, and the substrate sarcosine seems to enter the active site through either of these channels and reaches the re-side of the FAD isoalloxazine ring by traversing the mobile β-subunit C-terminal residues. The third channel goes through the α-subunit and has a folinic acid-binding site, where the iminium intermediate is converted to Gly and either formaldehyde or, 5,10-methylenetetrahydrofolate. Oxygen molecules are probably located on the surface cavity and diffuse to the FMN isoalloxazine ring; the H2O2 formed exits via the oxygen channel.
- Subjects
CORYNEBACTERIUM; SULFITES; FLAVINS; SARALASIN; FORMALDEHYDE; MOLECULES
- Publication
Journal of Biochemistry, 2010, Vol 148, Issue 4, p491
- ISSN
0021-924X
- Publication type
Article
- DOI
10.1093/jb/mvq083