Chlamydia protein's unusual shape may lead to new treatment

A Chlamydia protein's odd structure could mean new ways to diagnose and treat the sexually transmitted disease, University of Texas-San Antonio scientists said. Scientists at the university's school of medicine said the protein, Pgp3, which is secreted by the bacterium that causes Chlamydia, resembles the Eiffel Tower, the university said Thursday in a release. "From a structural standpoint, the protein is very odd indeed," said X-ray crystallographer P. John Hart, the Ewing Halsell President's Council Distinguished Chair in the Department of Biochemistry at the San Antonio medical school. "This long and slender molecule contains a fusion of structural motifs that resemble those typically found in viral and not bacterial proteins." Hart is co-lead author of the research, published in the Journal of Biological Chemistry. Co-lead author Guangming Zhong, a microbiology professor at the Health Science Center, said scientists aren't certain about the role the Pgp3 protein plays in chlamydia's development. "With the structural information uncovered in this paper, we can now test many hypotheses," Zhong said. The Pgp3 protein is a chlamydial virulence factor that is thought to enhance the bug's ability to infect its human host and evade host defenses, the university said. The protein is the second chlamydial virulence factor Zhong's laboratory identified, the university said. The first was a protein called CPAF. Structural studies have played a key role in understanding CPAF's functions in chlamydial infections, Zhong said. Centers for Disease Control and Prevention data indicate more than 1.4 million new cases of chlamydia were reported in 2011 across the United States. But the CDC said as many cases go unreported because most people with chlamydia exhibit no symptoms and aren't tested. Untreated, chlamydia can permanently damage a woman's reproductive system, possibly leading ectopic pregnancy, pelvic inflammatory disease and infertility.