The temperature activated HtrA protease from pathogen Chlamydia trachomatis acts as both a chaperone and protease at 37 °C

Characterization of the protease, HtrA, from pathogen Chlamydia trachomatis is presented. The purified recombinant protein was a serine endoprotease, specific for unfolded proteins, and temperature activated above 34 degrees C. Chaperone activity was observed, although this appeared target-dependent. Inactive protease (S247A) was able to chaperone insulin B-chain, irrespective of temperature, but at 30 degrees C only HtrA and not S247A displayed significant chaperone activity for alpha-lactalbumin. These data demonstrate that chaperone activity may involve functional protease domain and that C. trachomatis HtrA functions as both a chaperone and protease at 37 degrees C. These properties are consistent with the developmental cycle of this obligate intracellular bacterium. (c) 2007 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.