The Structure of the Cell-Wall Protease from Streptococci That Inactivates the Human Complement Factor 5A

The structure of a 949-residue fragment of complement factor 5a peptidase (SCP) was determined to 1.9 Å resolution. The molecule is made of five distinct domains in an elongated head–stalk structure. The structure suggests that activity of SCP can be modulated through binding of integrins to 2 RGD sequences. This structure is the first of an enzyme that is covalently attached to the cell wall of a Gram-positive bacteria. SCP is also the first functional protease containing a protease-associated domain to have its structure elucidated.