ATPase component of the type III secretion system (T3SS), also called injectisome, which is used to inject bacterial effector proteins into eukaryotic host cells (PubMed:24722491). Acts as a molecular motor to provide the energy that is required for the export of proteins (By similarity). Required for type III secretion apparatus (T3SA) formation, secretion of a subset of SPI-2 effectors and virulence (PubMed:24722491, PubMed:25035427). May play a critical role in T3SS substrate recognition, disassembly of the effector/chaperone complex and unfolding of the effector in an ATP-dependent manner prior to secretion (Probable). Releases the effector protein SseB from the T3SS-2 specific chaperone SsaE in an ATP-dependent manner (PubMed:24722491). ATP + H2O + cellular proteinSide 1 = ADP + phosphate + cellular proteinSide 2. The core secretion machinery of the T3SS is composed of approximately 20 different proteins, including cytoplasmic components, a base, an export apparatus and a needle (PubMed:30107569). This subunit is part of the cytosolic complex (PubMed:24722491). Forms homohexamers (PubMed:25035427). Forms a complex with SsaK/SctL (stator protein) and SsaQ/SctQ (the major sorting platform component) (PubMed:24722491). Interacts with the T3SS-2 specific chaperones SsaE, SseA, SscA, SscB, and SrcA (PubMed:24722491, PubMed:25035427). Can associate with the membrane regardless of the presence of the other ATPase-associated components. Deletion mutant cannot secrete the effector proteins SseB, SseC, SseD, SseF, SseG and SseJ (PubMed:24722491, PubMed:25035427). Mutant is also defective for the secretion of the translocon proteins SseC/SctE and SseD/SctB (PubMed:25035427). Mutant shows decreased virulence in the mouse model of systemic infection (PubMed:24722491). Belongs to the ATPase alpha/beta chains family. T3SS ATPase subfamily.