Part of the ESX-3 specialized secretion system, which is important for iron and zinc uptake or homeostasis (PubMed:19684129, PubMed:24155985). EccA3 exhibits ATPase activity and may provide energy for the export of ESX-3 substrates (By similarity). Part of the ESX-3 / type VII secretion system (T7SS), which is composed of cytosolic and membrane components. Repressed by IdeR in the presence of iron and by Zur in the presence of zinc. Belongs to the CbxX/CfxQ family.