May help regulate assembly and function of the type VII secretion system (T7SS) (PubMed:25865481). EsxA disassembles pre-formed EccC-EsxB multimers, possibly by making EccC-EsxA-EsxB trimers instead of EccC-EsxB-EsxB-EccC tetramers (PubMed:25865481). Forms a tight 1:1 complex with EsxB (PubMed:25865481). Forms a complex with EccC and EsxB, probably wholly mediated by EsxB (PubMed:25865481). Probably secreted via the ESX / type VII secretion system (T7SS). Belongs to the WXG100 family. ESAT-6 subfamily.