The host epithelium is both a barrier against, and the target for microbial
infections. Maintaining regulated cell growth ensures an intact protective layer towards microbial-induced cellular damage. Neisseria gonorrhoeae
infections disrupt host cell cycle regulation machinery and the
infection causes
DNA double strand breaks that delay progression through the G2/M phase. We show that intracellular gonococci upregulate and release
restriction endonucleases that enter the nucleus and damage human chromosomal
DNA.
Bacterial lysates containing
restriction endonucleases were able to fragment genomic
DNA as detected by PFGE. Lysates were also microinjected into the cytoplasm of cells in interphase and after 20
h, DNA double strand breaks were identified by 53BP1 staining. In addition, by using live-cell microscopy and NHS-
ester stained live gonococci we visualized the subcellular location of the bacteria upon mitosis. Infected cells show dysregulation of the spindle assembly checkpoint
proteins MAD1 and MAD2, impaired and prolonged M-phase, nuclear swelling, micronuclei formation and
chromosomal instability. These data highlight basic molecular functions of how gonococcal
infections affect host cell cycle regulation, cause
DNA double strand breaks and predispose cellular
malignancies.