Part of the ESX-1 / type VII specialized secretion system (T7SS), which exports several proteins including EsxA and EsxB (Probable). Plays a role in DNA conjugation, in at least a donor strain (PubMed:15314236). Increases efficiency of DNA conjugation when disrupted in donor strain (PubMed:15314236). DNA conjugation in M.smegmatis is unidirectional with distinct donor and recipient strains; mc(2)155 is a donor strain while MKD8 is a recipient strain. Mutations in a donor strain that alter DNA transfer do not always alter DNA transfer in a recipient strain. Belongs to the mycobacterial PE family.