Required for YukE secretion. Probable component or regulator of the ESX/ESAT-6-like secretion system (BsEss) (PubMed:23861817, PubMed:24798022). Required to deliver LXG toxins to target cells (PubMed:34280190). Cells lacking this gene are blocked in YukE secretion (PubMed:23861817, PubMed:24798022). They display an increased bacteriophage SPP1 resistance phenotype (PubMed:15576783). Loss of delivery of LXG toxins to target cells (PubMed:34280190). Belongs to the EssB family.