Chlamydia trachomatis cryptic plasmid

The Chlamydia trachomatis cryptic plasmid is a 7.5-kb circular DNA molecule present in most isolates of this obligate intracellular bacterium, encoding eight open reading frames (ORFs) such as pgp1-8 that are critical for plasmid replication, maintenance, and gene regulation. It functions as a transcriptional regulator of both plasmid-encoded and chromosomal genes, with proteins like Pgp4 acting as a master regulator influencing virulence factors, glycogen accumulation, inclusion morphology, and genes involved in type III secretion and outer membrane proteins. The plasmid expresses small non-coding RNAs (sRNAs), including abundant ones like pL2-sRNA1, which likely control plasmid partitioning, replication, and possibly chromosomal gene expression in antisense orientations. Plasmid-free strains exhibit attenuated phenotypes, such as abnormal reticulate body development and reduced infectivity, underscoring its role in bacterial fitness and pathogenesis. In disease, it contributes to chlamydial infections of the genital tract, eyes, and respiratory system by modulating host interaction and bacterial survival, making it a key element in C. trachomatis virulence.

Other names

C. trachomatis plasmidChlamydia trachomatis plasmid7.5-kb plasmid