This domain is found at the N-terminal end of ESX-1 secretion system protein EccA1 from Mycobacterium tuberculosis and similar proteins predominantly from Actinobacteria. EccA1 is part of the ESX-1 specialised secretion system (a cluster of the type VII secretion system, T7SS). EccA1 contains a C-terminal ATPase domain (Pfam:PF00004 and Pfam:PF17866) and a tetratricopeptide repeat (TPR) containing N-terminal domain (this entry). The six tandem TPR motifs of this domain packed in parallel create a series of repeating antiparallel alpha-helices that give rise to an overall superhelix structure [1,2].

1: Self-recognition mechanism of MamA, a magnetosome-associated TPR-containing protein, promotes complex assembly. Zeytuni N, Ozyamak E, Ben-Harush K, Davidov G, Levin M, Gat Y, Moyal T, Brik A, Komeili A, Zarivach R; Proc Natl Acad Sci U S A. 2011;108:E480-E487. PMID:21784982

2: Crystal structure of the N-terminal domain of EccA(1) ATPase from the ESX-1 secretion system of Mycobacterium tuberculosis. Wagner JM, Evans TJ, Korotkov KV; Proteins. 2014;82:159-163. PMID:23818233