This domain is found in the fatty acid synthase (FAS) complex present in species such as Mycobacterium smegmatis and Thermomyces lanuginosus. FAS is a homo-hexameric enzyme that catalyzes synthesis of fatty acid precursors of mycolic acids. This domain is composed of dimerization module 1 (DM1) and four-helix bundle (4HB), both of which are conserved parts of the acetyl transferase [1].

1: 7.5-A cryo-em structure of the mycobacterial fatty acid synthase. Boehringer D, Ban N, Leibundgut M; J Mol Biol. 2013;425:841-849. PMID:23291528