Part of a sulfur-relay system required for 2-thiolation of 5-methylaminomethyl-2-thiouridine (mnm(5)s(2)U) at tRNA wobble positions. Heterohexamer, formed by a dimer of trimers. The hexameric TusBCD complex contains 2 copies each of TusB, TusC and TusD. The TusBCD complex interacts with TusE. Belongs to the DsrF/TusC family.