tRNA modification enzyme MiaB connects environmental cues to activation of Pseudomonas aeruginosa type III secretion system

• Published in: PLoS pathogens Vol. 18; no. 12; p. e1011027
• Main Authors: Lin, Qiqi, Huang, Jiahui, Liu, Zhiqing, Chen, Qunyi, Wang, Xinbo, Yu, Guohui, Cheng, Ping, Zhang, Lian-Hui, Xu, Zeling
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 01.12.2022; Public Library of Science (PLoS)
• Subjects: Bacterial infections; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biology and Life Sciences; Cellular signal transduction; Cues; Cytotoxicity; Drug resistance; E coli; Effector cells; Environmental changes; Environmental conditions; Enzymes; Epithelial cells; Epithelium; Gene expression; Gene Expression Regulation, Bacterial; Genetic aspects; Humans; Kinases; Medicine and Health Sciences; Metabolic disorders; Microbial enzymes; Microbiological research; Nosocomial infections; Opportunist infection; Pathogens; Physiological aspects; Proteins; Pseudomonas aeruginosa; Pseudomonas aeruginosa - metabolism; Regulatory mechanisms (biology); RNA, Transfer - metabolism; Signal transduction; Signaling; Spermidine; Spermidine - metabolism; Toxicity; Transfer RNA; tRNA; tRNA Ala; Type III Secretion Systems - genetics; Type III Secretion Systems - metabolism; Virulence; Virulence (Microbiology); Virulence factors; China
• ISSN: 1553-7374; 1553-7366; 1553-7374
• DOI: 10.1371/journal.ppat.1011027

Pseudomonas aeruginosa, a major inhabitant of numerous environmental reservoirs, is a momentous opportunistic human pathogen associated with severe infections even death in the patients suffering from immune deficiencies or metabolic diseases. Type III secretion system (T3SS) employed by P. aeruginosa to inject effector proteins into host cells is one of the pivotal virulence factors pertaining to acute infections caused by this pathogen. Previous studies showed that P. aeruginosa T3SS is regulated by various environmental cues such as calcium concentration and the host signal spermidine. However, how T3SS is regulated and expressed particularly under the ever-changing environmental conditions remains largely elusive. In this study, we reported that a tRNA modification enzyme PA3980, designated as MiaB, positively regulated T3SS gene expression in P. aeruginosa and was essential for the induced cytotoxicity of human lung epithelial cells. Further genetic assays revealed that MiaB promoted T3SS gene expression by repressing the LadS-Gac/Rsm signaling pathway and through the T3SS master regulator ExsA. Interestingly, ladS, gacA, rsmY and rsmZ in the LadS-Gac/Rsm signaling pathway seemed potential targets under the independent regulation of MiaB. Moreover, expression of MiaB was found to be induced by the cAMP-dependent global regulator Vfr as well as the spermidine transporter-dependent signaling pathway and thereafter functioned to mediate their regulation on the T3SS gene expression. Together, these results revealed a novel regulatory mechanism for MiaB, with which it integrates different environmental cues to modulate T3SS gene expression in this important bacterial pathogen.