AUTHOR=Wang Dan , Li Hong , Ma Xiang , Tang Yanqiong , Tang Hongqian , Hu Xinwen , Liu Zhu 

TITLE=Small RNA AvrA Regulates IscR to Increase the Stress Tolerances in SmpB Deficiency of Aeromonas veronii

JOURNAL=Frontiers in Cellular and Infection Microbiology

VOLUME=Volume 9 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/cellular-and-infection-microbiology/articles/10.3389/fcimb.2019.00142

DOI=10.3389/fcimb.2019.00142

ISSN=2235-2988

ABSTRACT=The superbacteria Aeromonas veronii behaves not only a strong pathogenicity but also the resistances to nine kinds of antibiotics, resulting in the economic losses and health hazards. Small Protein B (SmpB) plays important roles in protein quality control, virulence, and stress reactions. The transcriptomic data revealed the expressions of type IV pilus assembly and type VI secretion system (T6SS) proteins were downregulated in SmpB deficiency, indicating that the virulence of A. veronii might be attenuated. Although SmpB deletion decreased the colonization in the mice spleen and liver, LD50 of smpB mutant did not alter as expected compared with the wild type. Further the transcriptomic and quantitative RT-PCR analyses showed that the combination of the downregulated AvrA and the upregulated iron-sulfur protein activator IscR, which mediated the oxidative tolerance in smpB deletion. Next a reporter plasmid was constructed in which the promoter of iscR was applied to control the expression of the enhanced green fluorescent protein (eGFP) gene. When the reporter plasmid was co-expressed with the AvrA expression into E. coli, the relative fluorescence intensity was decreased significantly, suggesting that AvrA bound iscR mRNA by base pairing, which in turn relieved the inhibition of iscR and intensified the downstream iron-sulfur proteins. Collectively, smpB mutant exhibited the attenuated virulence in mice and the enhanced tolerances to oxidative stress. This study demonstrates the complexity of gene regulation network mediated by sRNA in system biology, and also reflects the strong adaptability of superbacteria A. veronii in the process of evolution.