AUTHOR=Gu Qibing , He Peijuan , Wang Dan , Ma Jiale , Zhong Xiaojun , Zhu Yinchu , Zhang Yue , Bai Qiankun , Pan Zihao , Yao Huochun 

TITLE=An Auto-Regulating Type II Toxin-Antitoxin System Modulates Drug Resistance and Virulence in Streptococcus suis

JOURNAL=Frontiers in Microbiology

VOLUME=12

YEAR=2021

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2021.671706

DOI=10.3389/fmicb.2021.671706

ISSN=1664-302X

ABSTRACT=<p>Toxin-antitoxin (TA) systems are ubiquitous genetic elements that play an essential role in multidrug tolerance and virulence <italic>of bacteria</italic>. So far, little is known about the TA systems in <italic>Streptococcus suis</italic>. In this study, the Xress-MNTss TA system, composed of the MNTss toxin in the periplasmic space and its interacting Xress antitoxin, was identified in <italic>S. suis</italic>. β-galactosidase activity and electrophoretic mobility shift assay (EMSA) revealed that Xress and the Xress-MNTss complex could bind directly to the Xress-MNTss promoter as well as downregulate streptomycin adenylyltransferase <italic>ZY05719_RS04610</italic>. Interestingly, the Xress deletion mutant was less pathogenic <italic>in vivo</italic> following a challenge in mice. Transmission electron microscopy and adhesion assays pointed to a significantly thinner capsule but greater biofilm-formation capacity in Δ<italic>Xress</italic> than in the wild-type strain. These results indicate that Xress-MNTss, a new type II TA system, plays an important role in antibiotic resistance and pathogenicity in <italic>S. suis</italic>.</p>