Part of an export system, which is required for biosynthesis and secretion of siderophores. Overexpression of the system confers non-target based resistance to azoles, clofazimine and bedaquiline, via an efflux mechanism. Interacts with MmpS5. Can also interact with MmpS4. Repressed by MmpR5 (PubMed:24590481, PubMed:24737322). Repressed by iron (PubMed:12065475). Regulation is IdeR-independent (PubMed:12065475). Belongs to the resistance-nodulation-cell division (RND) (TC 2.A.6) family. MmpL subfamily.