AUTHOR=Ni Muyang , Lin Jianzhong , Gu Jiayu , Lin Shituan , He Mei , Guo Yunxue 

TITLE=Antitoxin CrlA of CrlTA Toxin–Antitoxin System in a Clinical Isolate Pseudomonas aeruginosa Inhibits Lytic Phage Infection

JOURNAL=Frontiers in Microbiology

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2022.892021

DOI=10.3389/fmicb.2022.892021

ISSN=1664-302X

ABSTRACT=<p><italic>Pseudomonas aeruginosa</italic> is an important opportunistic pathogen in cystic fibrosis patients and immunocompromised individuals, and the toxin–antitoxin (TA) system is involved in bacterial virulence and phage resistance. However, the roles of TA systems in <italic>P. aeruginosa</italic> are relatively less studied and no phage Cro-like regulators were identified as TA components. Here, we identified and characterized a chromosome-encoded prophage <underline>Cr</underline>o-<underline>l</underline>ike <underline>a</underline>ntitoxin (CrlA) in the clinical isolate <italic>P. aeruginosa</italic> WK172. CrlA neutralized the toxicity of the <underline>t</underline>oxin <underline>Crl</underline>A (CrlT) which cleaves mRNA, and they formed a type II TA system. Specifically, <italic>crlA</italic> and <italic>crlT</italic> are co-transcribed and their protein products interact with each other directly. The autorepression of CrlA is abolished by CrlT through the formation of the CrlTA complex. Furthermore, <italic>crlTA</italic> is induced in the stationary phase, and <italic>crlA</italic> is expressed at higher levels than <italic>crlT</italic>. The excess CrlA inhibits the infection of lytic <italic>Pseudomonas</italic> phages. CrlA is widely distributed among <italic>Pseudomonas</italic> and in other bacterial strains and may provide antiphage activities.</p>