Required for assembly of the protein secretion apparatus HSI-I. Actively secreted during chronic infection of cystic fibrosis patients. Hexamer. Three hcp1 monomers form two closely related hexameric rings with a 40 Angstrom internal diameter. Transcriptionally repressed by RetS and activated by LadS. ATP hydrolysis by the first AAA domain of ClpV1 is required for Hcp1 secretion. Belongs to the hcp1 family.