ClpV3 of the H3-Type VI Secretion System (H3-T6SS) Affects Multiple Virulence Factors in Pseudomonas aeruginosa

• Published in: Frontiers in microbiology Vol. 11; p. 1096
• Main Authors: Li, Yanqi, Chen, Lin, Zhang, Pansong, Bhagirath, Anjali Y., Duan, Kangmin
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 29.05.2020
• Subjects: ClpV3; Microbiology; Pseudomonas aeruginosa; secretion system; signal molecules; virulence factors; Pseudomonas aeruginosa; secretion system; signal molecules; ClpV3; virulence factors
• ISSN: 1664-302X; 1664-302X
• DOI: 10.3389/fmicb.2020.01096

The type VI secretion system (T6SS) is a toxic effector delivery apparatus widely distributed in Gram-negative bacteria. The opportunistic pathogen encodes three T6SSs, namely H1-, H2-, and H3-T6SS. Each T6SS possesses its own effectors and their roles are not yet fully understood. Here, we report that an H3-T6SS deletion mutant PAO1(Δ ) significantly affected the virulence-related phenotypes including pyocyanin production, biofilm formation, proteolytic activity, and motilities. Most interestingly, the expression of T3SS genes was markedly affected, indicating a link between H3-T6SS and T3SS. RNA-Sequencing was performed to globally identify the genes differentially expressed when H3-T6SS was inactivated and the results obtained correlated well with the observed phenotypes. Interestingly, the expressions of T2SS, T3SS, H2-T6SS, and H3-T6SS were all significantly decreased, while H1-T6SS was increased in the PAO1(Δ ) strain. We also observed that the intracellular concentration of secondary messenger cAMP was reduced in PAO1(Δ ), and the c-di-GMP level was also decreased as indicated by the decreased reporter activity. Finally, by using a infection model, we show that H3-T6SS plays a key role in the pathogenicity of . Overall, our study highlights the unique connection of H3-T6SS in with T3SS, pyocyanin production, biofilm formation and pathogenicity.