Research on the Regulation of the Chlamydia trachomatis Developmental Cycle

Chlamydia trachomatis is an obligate intracellular bacterium that undergoes differentiation, repli cation, and re-differentiation within host cells to complete its developmental cycle. C. trachomatis has a unique bipha sic developmental cycle that comprises two functionally and morphologically distinct forms. The first form called EB (elementary body), is infectious but non-replicative, can entering a host cell by endocytosis. Within 6-8 h post infec tion, the EB differentiates into a metabolically active, non-infectious but replicative RB (reticular body). RB replicates via multiple rounds of binary fission and then re-differentiates to an EB. The newly formed EB is then released and is ready to infect new host cells. C. trachomatis possesses a small chromosome of 1.04 Mb, encoding approximately 900 proteins including several regulatory factors. The early genes are transcribed at first few hours of infection, as well as genes transcribed at mid-cycle playing critical role during RB replication, while late genes are activated at RB-EB differentiation. The regulatory mechanism of gene expression in C. trachomatis is complex, involving transcription factors and σ factors. Regulators controls gene expression by sensing environmental changes and metabolic signals to ensure that C. trachomatis adapts to different growth conditions. C. trachomatis could be able to enter the “persistent” state at an adverse growth condition, in which RB stopped dividing and enlarged its size. Infectious EB is generated when the growth conditions are recovered. This review summarized the main events during the C. trachomatis devel opmental cycle and the regulatory mechanisms that governing each stage at the transcriptional level. In addition, this study explained the mechanism by which transcription factors regulate C. trachomatis gene expression to adapt for extracellular survival environmental changes.

CSTR: 32200.14.cjcb.2025.11.0025