The Chlamydial Protease CPAF
Julie A. Brothwell, Christine Sütterlin, Thomas Rudel and Ming Tan
from: Chlamydia Biology: From Genome to Disease (Edited by: Ming Tan, Johannes H. Hegemann and Christine Sütterlin). Caister Academic Press, U.K. (2020) Pages: 177-194.
CPAF is a conserved chlamydial protease, but our understanding of its role in a Chlamydia infection is incomplete and evolving. CPAF is expressed as an inactive enzyme that requires secretion, homodimerization, and proteolytic processing for conversion into the active protease. It cleaves or degrades many chlamydial and host proteins, but it has been challenging to distinguish in vivo substrates that are true biological targets from in vitro substrates that do not undergo proteolysis during a Chlamydia infection. The subcellular localization of active CPAF in a Chlamydia-infected cell is also controversial because it is uncertain whether it is primarily localized in the chlamydial inclusion during infection or also present in the host cytoplasm. CPAF activity must be regulated to account for the observed differences between in vitro substrate susceptibility and in vivo proteolysis, but the control mechanisms have not been completely defined. Multiple functions have been proposed for CPAF. The strongest data indicate that CPAF modulates the host immune response by down-regulating the type I interferon response and by inhibiting neutrophil activation.In vivo, CPAF is necessary to maintain the Chlamydia infection in the genital tract of mice. CPAF is also a protective antigen that is being studied as a vaccine candidate. Thus, despite the controversy surrounding the true substrates of CPAF, CPAF remains an important virulence factor of Chlamydia read more ...