Related Experiment Video
Updated: Mar 28, 2026

Forward Genetic Approaches in Chlamydia trachomatis
Published on: October 23, 2013
Coordinated topoisomerase function shapes the fluoroquinolone response of Chlamydia trachomatis
Andrew Terrebonne1, Caitlynn Diggs1, Scot P Ouellette2
1Department of Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, LA 70112.
Abstract:
DNA supercoiling is essential for the developmental cycle of Chlamydia trachomatis, yet its role in shaping antibiotic responses remains poorly understood. We investigated how the fluoroquinolone moxifloxacin (Mox) influenced C. trachomatis growth across developmental stages with its distinct supercoiling levels. Early Mox exposure completely halted bacterial growth, whereas treatment during mid-cycle produced enlarged, persistent forms and abolished formation of infectious progeny. These stage-specific outcomes coincided with inhibition of DNA replication, depletion of DNA gyrase, and transcriptional repression of ompA and omcB, accompanied by preserved or elevated expression of the stress-responsive groESL1 operon. Mox also elicited compensatory downregulation of topoisomerase I (TopA), consistent with attempts to rebalance intracellular supercoiling. Together, these data demonstrate that fluoroquinolone susceptibility in C. trachomatis reflects stage-dependent supercoiling levels. Perturbation of supercoiling homeostasis drives developmental arrest and persistence phenotypes, highlighting coordinated gyrase-TopA activity as a key determinant of fluoroquinolone tolerance and a potential target for overcoming persistent infection.
Related Concept Videos
Inhibitors of Bacterial DNA Synthesis
DNA Topoisomerases
Types and Mechanism of action
Topoisomerases are divided into two main types. ...
Bacterial Phylum Chlamydiae
Conservative Site-specific Recombination and Phase Variation
The recognition sites for Cre recombinase called LoxP...
Coordination of Gene Expression Processes in Bacteria
Translesion DNA Polymerases
TLS polymerases are found in all three domains of life - archaea, bacteria, and eukaryotes. Of the different classes of TLS polymerases, members of the Y family are fitted with specialized structures that...

