Crystal structure of the N-terminal domain of EccA₁ ATPase from the ESX-1 secretion system of Mycobacterium tuberculosis

EccA₁ is an important component of the type VII secretion system (T7SS) that is responsible for transport of virulence factors in pathogenic mycobacteria. EccA₁ has an N-terminal domain of unknown function and a C-terminal AAA+ (ATPases associated with various cellular activities) domain. Here we report the crystal structure of the N-terminal domain of EccA₁ from Mycobacterium tuberculosis, which shows an arrangement of six tetratricopeptide repeats that may mediate interactions of EccA₁ with secreted substrates. Furthermore, the size and shape of the N-terminal domain suggest its orientation in the context of a hexamer model of full-length EccA₁.