Involved in DNA conjugation in the recipient strain (PubMed:18554329). Loss of DNA conjugation when disrupted in recipient strain, strain still secretes EsxB (PubMed:18554329). In the well characterized mc(2)155 strain this gene not present; it is part of an MKD8 strain-specific insert (RSR-II) between MSMEG_5168 and MSMEG_5169. 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.