Zinc-dependent endoprotease with a unique preference for proline residues surrounding the scissile bond. Exhibits a high preference for an asparagine at the P2 position and hydrophobic residues (Val, Ile, Leu) at the P3 position. Efficiently cleaves the LPXTG cell surface proteins CD630_28310 and CD630_32460 at multiple cleavage sites in vivo. Has a role in the regulation of C.difficile adhesion versus motility by cleaving surface adhesion proteins such as the collagen binding protein CD630_28310, and is important for efficient infection. Is also able to cleave fibronectin and fibrinogen in vitro; cleaves at the N-terminus of the beta-chain of fibrinogen. Destabilizes the fibronectin network produced by human fibroblasts. Therefore, may be important in key steps of clostridial pathogenesis by degrading extracellular matrix components associated with the gut epithelial cells. To a lesser extent, IgA1, IgA2, and human HSP 90-beta, but not HSP 90-alpha, are also substrates for the enzyme. Is not active on different collagen types, casein and gelatin. The enzyme catalyzes the hydrolytic cleavage of peptide bonds between two proline residues. Binds 1 zinc ion per subunit. Is inhibited by the chelating agent o-phenanthroline in vitro. kcat is 19 sec(-1) with synthetic FRET peptide DabcylLys-EVNPPPPD-EdansGlu as substrate. Monomer. Expression is controlled by a type I c-diGMP riboswitch; elevated levels of c-diGMP repress transcription of zmp1. The structure of Zmp1 is similar to anthrax lethal factor (LF) metalloprotease domain IV. The S-loop of Zmp1 undergoes large motions upon substrate binding and seems to exhibit a function analogous to that of LF domain III, thus contributing to sequence specificity and substrate binding. An aliphatic-aromatic network and the diverting loop contribute to Pro-Pro specificity. Cells lacking this gene retain CD630_28310 on the cell surface, show higher affinity for collagen type I with attenuated virulence in a hamster model of infection. Belongs to the peptidase M34 family. Pro-Pro endopeptidase subfamily.