The Gram-positive bacterium Enterococcus faecalis is currently
one of the major pathogens of nosocomial infections.
The lifestyle of E. faecalis relies primarily on its remarkable capacity
to face and survive in harsh environmental conditions.
Toxin-antitoxin (TA) systems have been linked to the growth
control of bacteria in response to adverse environments but
have rarely been reported in Enterococcus. Three functional
type II TA systems were identified among the 10 putative
TA systems encoded by E. faecalis ATCC29212. These toxin
genes have conserved domains homologous to MazF (DR75_
1948) and ImmA/IrrE family metallo-endopeptidases (DR75_
1673 and DR75_2160). Overexpression of toxin genes could
inhibit the growth of Escherichia coli. However, the toxin
DR75_1673 could not inhibit bacterial growth, and the bacteriostatic
effect occurred only when it was coexpressed with
the antitoxin DR75_1672. DR75_1948–DR75_1949 and DR75_
160–DR75_2161 could maintain the stable inheritance of the
unstable plasmid pLMO12102 in E. coli. Moreover, the transcription
levels of these TAs showed significant differences
when cultivated under normal conditions and with different
temperatures, antibiotics, anaerobic agents and H2O2. When
DR75_2161 was knocked out, the growth of the mutant strain
at high temperature and oxidative stress was limited. The experimental
characterization of these TAs loci might be helpful
to investigate the key roles of type II TA systems in the
physiology and environmental stress responses of Enterococcus.
Unveiling the impact of antibiotic stress on biofilm formation and expression of toxin-antitoxin system genes in Clostridium difficile clinical isolates Nasim Cheraghi, Saeed Khoshnood, Nourkhoda Sadeghifard, Niloufar Khodaei, Parisa Asadollahi, Saiyad Bastaminejad, Ebrahim Kouhsari, Nazanin Omidi, Behrooz Sadeghi Kalani Molecular Biology Reports.2024;[Epub] CrossRef
Edwardsiella piscicida HigB: A type II toxin that is essential to oxidative resistance, biofilm formation, serum survival, intracellular propagation, and host infection Jinhong Xie, Qianyun Zhao, Huiqin Huang, Zaiguang Fang, Yonghua Hu Aquaculture.2021; 535: 736382. CrossRef