Project name: Chlamydia trachomatis

Description: The serovar A and D strains were previously compared using microarrays and found to be 99% identical. The major differences that could affect pathogenicity were in the plasticity zone, ompA, and in the polymorphic membrane protein (pmp) family. Other comparisons showed that STD serovars have a trytophan synthase operon, while ocular serovars have a mutated copy, which is important due to the trytophan-limiting properties that result from interferon-gamma induction during infection. STD serovars also have a putative GTPase-inactivating protein (CT166). Sequence comparison demonstrated that there are only two coding regions that are present in the serovar A strain but are absent in serovar D: CTA_0177 and CTA_0178. There is less than 2 Kb difference in DNA sequence between the two strains and most of these differences lie in the plasticity zone. There is an in-frame deletion in the translocated actin-recruitig phosphoprotin (Tarp; CTA_0498/CT456) and an in-frame fusion of two small unannotated ORFs in the serovar D genome (CTA_0934) which is uniquely found in ocular serovars. The Tarp protein is a type III secreted protein that actively recruits actin and many of the changes occur at the 5' and 3' ends of the genes via recombination resulting in a number of variabale repeat units (approximately 50 amino acids long) occurring in either genome. These changes may affect the invasive properties of the different serovars. A number of other coding regions are also disrupted including the previously described inactivated trytophan operon, as well as some hypothetical proteins. Differences were also found in the pmp family of genes that are similar to autotransporters and the polymorphisms may affect virulence function.

Last updated: 2005-09-28