Component of the type VII secretion system (Ess) (Probable). Plays a role in Ess secretion during infection. Required for the efficient secretion of EsxA. Required for abscess formation and staphylococcal persistence in host tissue (PubMed:21278286). Possesses a toxic DNase activity that is modulated by EssG by forming a nuclease toxin-antitoxin pair. This nuclease toxin targets competitor bacteria (By similarity). Interacts (via C-terminal) with EssG; this interaction blocks EssD activity. Interacts with EssE. Released from the cell in a form that is immediately active while EssG partner protein remains in the producing cell where it may potentially serve further protective functions. Expression is activated by mutations in esaB and essB (newman). Deletions mutants generate fewer abscesses with a reduced bacterial load compared to wild-type strain. Belongs to the EssD family.