Production, crystallization and X-ray diffraction analysis of the protease CT441 from Chlamydia trachomatis

The prokaryotic obligate intracellular pathogen Chlamydia trachomatis is the most prevalent cause of preventable blindness, affecting approximately six million people worldwide. In addition, C. trachomatis is the most commonly reported sexually transmitted pathogen in Europe and the US, causing pelvic inflammation, ectopic pregnancy and infertility. As in other intracellular pathogens, proteases play crucial roles during most stages of the complex life cycle of Chlamydia. CT441 is a chlamydial protease that has been reported to interfere with oestrogen signalling of the host cell. Here, the recombinant production, purification and crystallization of an inactive variant of CT441, designated CT441° (active-site Ser455 replaced by Ala), are described. CT441° was crystallized in space group P22121, with unit-cell parameters a = 86.7, b = 184.0, c = 209.6 Å. A complete diffraction data set was collected to a resolution of 2.95 Å.