Part of a complex that provides reducing equivalents for heterodisulfide reductase. MvhD may form the contact site for heterodisulfide reductase. Binds 1 [2Fe-2S] cluster. The F420-non-reducing hydrogenase is composed of three subunits; MvhA, MvhD and MvhG. It forms a complex with the heterodisulfide reductase (Hdr). Belongs to the MvhD/VhuD family.