Clostridium difficile secreted Pro-Pro endopeptidase PPEP-1 (ZMP1/CD2830) modulates adhesion through cleavage of the collagen binding protein CD2831.

The Clostridium difficile cd2830 gene product is a secreted metalloprotease, named Pro-Pro endopeptidase (PPEP-1). PPEP-1 cleaves C. difficile cell surface proteins (e.g. CD2831). Here, we confirmed that PPEP-1 has a unique preference for prolines surrounding the scissile bond. Moreover, we show that it exhibits a high preference for an asparagine at the P2 position and hydrophobic residues at the P3 position. Using a PPEP-1 knockout C. difficile strain, we demonstrate that the removal of the collagen binding protein CD2831 is fully attributable to PPEP-1 activity. The PPEP-1 knockout strain demonstrated higher affinity for collagen type I with attenuated virulence in hamsters.