A characteristic of polymorphic membrane protein F of Chlamydia trachomatis isolated from male urogenital tracts in Japan

Although sexually transmitted disease due to Chlamydia trachomatis occurs similarly in both men and women, the female urogenital tract differs from that of males anatomically and physiologically, possibly leading to specific polymorphisms of the bacterial surface molecules. In the present study, we therefore characterized polymorphic features in a high-definition phylogenetic marker, polymorphic outer membrane protein (Pmp) F of C. trachomatis strains isolated from male urogenital tracts in Japan (Category: Japan-males, n = 12), when compared with those isolated from female cervical ducts in Japan (Category: Japan-females, n = 11), female cervical ducts in the other country (Category: Ref-females, n = 12) or homosexual male rectums in the other country (Category: Ref-males, n = 7), by general bioinformatics analysis tool with MAFFT software. As a result, phylogenetic reconstruction of the PmpF amino acid sequences showing three distinct clusters revealed that the Japan-males were limited into cluster 1 and 2, although there were only four clusters even though including an outgroup. Meanwhile, the phylogenetic distance values of PmpF passenger domain without hinge region, but not its full-length sequence, showed that the Japan-males were more stable and displayed less diversity when compared with the other categories, supported by the sequence conservation features. Thus, PmpF passenger domain is a useful phylogenetic maker, and the phylogenic features indicate that C. trachomatis strains isolated from male urogenital tracts in Japan may be unique, suggesting an adaptation depending on selective pressure, such as the presence or absence of microbial flora, furthermore possibly connecting to sexual differentiation.