This domain is found in the MbtH protein Swiss:O05821 as well as at the N terminus of the antibiotic synthesis protein NIKP1. MbtH and its homologues were first noted in gene clusters involved in non-ribosomal peptides and other secondary metabolites by Quadri et al [1]. This domain is about 70 amino acids long and contains 3 fully conserved tryptophan residues [2]. The structure of the PA2412 protein shows it adopts a beta-beta-beta-alpha-alpha topology with the short C-terminal helix forming the tip of an overall arrowhead shape [3]. MbtH proteins have been shown to be required for the synthesis of antibiotics, siderophores and glycopeptidolipids [3-6].

1: Identification of a Mycobacterium tuberculosis gene cluster encoding the biosynthetic enzymes for assembly of the virulence-conferring siderophore mycobactin. Quadri LE, Sello J, Keating TA, Weinreb PH, Walsh CT; Chem Biol. 1998;5:631-645. PMID:9831524

2: New Knowledge from Old: In silico discovery of novel protein domains in Streptomyces coelicolor. Yeats C, Bentley S, Bateman A; BMC Microbiol 2003;3:3-3. PMID:12625841

3: The 1.8 A crystal structure of PA2412, an MbtH-like protein from the pyoverdine cluster of Pseudomonas aeruginosa. Drake EJ, Cao J, Qu J, Shah MB, Straubinger RM, Gulick AM; J Biol Chem. 2007;282:20425-20434. PMID:17502378

4: Effects of deletions of mbtH-like genes on clorobiocin biosynthesis in Streptomyces coelicolor. Wolpert M, Gust B, Kammerer B, Heide L; Microbiology. 2007;153:1413-1423. PMID:17464055

5: MbtH-like protein-mediated cross-talk between non-ribosomal peptide antibiotic and siderophore biosynthetic pathways in Streptomyces coelicolor M145. Lautru S, Oves-Costales D, Pernodet JL, Challis GL; Microbiology. 2007;153:1405-1412. PMID:17464054

6: Production of mycobacterial cell wall glycopeptidolipids requires a member of the MbtH-like protein family. Tatham E, Chavadi S, Mohandas P, Edupuganti U, Angala S, Chatterjee D, Quadri LE; BMC Microbiol. 2012;12:118. PMID:22726990