Crystal structure of heterotetrameric sarcosine oxidase from Corynebacterium sp. U-96

Sarcosine oxidase from Corynebacterium sp. U-96 is a heterotetrameric enzyme. Here we report the crystal structures of the enzyme in complex with dimethylglycine and folinic acid. The α subunit is composed of two domains, contains NAD+, and binds folinic acid. The β subunit contains dimethylglycine, FAD, and FMN, and these flavins are approximately 10 Å apart. The γ subunit is in contact with two domains of α subunit and has possibly a folate-binding structure. The δ subunit contains a single atom of zinc and has a Cys3His zinc finger structure. Based on the structures determined and on the previous works, the structure-function relationship on the heterotetrameric sarcosine oxidase is discussed.