Pseudomonas aeruginosa 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 P. aeruginosa are relatively less studied and no phage Cro-like regulators were identified as TA components. Here, we identified and characterized a chromosome-encoded prophage Cro-like antitoxin (CrlA) in the clinical isolate P. aeruginosa WK172. CrlA neutralized the toxicity of the toxin CrlA (CrlT) which cleaves mRNA, and they formed a type II TA system. Specifically, crlA and crlT 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, crlTA is induced in the stationary phase, and crlA is expressed at higher levels than crlT. The excess CrlA inhibits the infection of lytic Pseudomonas phages. CrlA is widely distributed among Pseudomonas and in other bacterial strains and may provide antiphage activities.
Since the outbreak of novel coronavirus pneumonia, the sales of non-essential commodities, catering industry and entertainment industry have been significantly affected. In order to effectively deal with the impact on the epidemic of consumption, various regions and departments have successively issued policies and measures to expand consumption. The issuance of consumer coupons is one of the major measures. This paper analyzes the utility of consumer coupons and the peculiarities of China's environment, and researches the feasibility of issuing consumer coupons based on the analysis results. Finally, it proposes specific countermeasures and suggestions for the problem in the issuance, which provide a theoretical basis of the issuance of consumer coupons.
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