Involved in the regulation of the iron regulon in responss to decreased mitochondrial iron-sulfur cluster synthesis. Release of any N-terminal amino acid, including proline, that is linked to proline, even from a dipeptide or tripeptide. Binds 2 manganese ions per subunit. Homodimer (By similarity). Interacts with FRA2. Present with 3237 molecules/cell in log phase SD medium. Belongs to the peptidase M24B family.