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

Abstract

The superbacteria Aeromonas veronii displays not only a strong pathogenicity but also the resistance to nine kinds of antibiotics, resulting in the economic losses and health hazards. Small Protein B (SmpB) plays an important role in protein quality control, virulence, and stress reactions. Transcriptomic data revealed that expressions of the 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 colonization in the mouse spleen and liver, LD50 of the smpB mutant was not altered 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, 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 to iscR mRNA by base pairing, which in turn relieved the inhibition of iscR and intensified the downstream iron-sulfur proteins. Collectively, the smpB mutant exhibited an attenuated virulence in mice and enhanced tolerances to oxidative stress. This study demonstrates the complexity of gene regulation networks mediated by sRNA in systems biology, and also reflects the strong adaptability of superbacteria A. veronii in the process of evolution.

SmpB and tmRNA Orchestrate Purine Pathway for the Trimethoprim Resistance in Aeromonas veronii

“…In addition to the trans-translation function of SmpB and tmRNA, they also play other roles in bacteria. As a transcription factor, SmpB participates in transcriptional regulation of bvgS and sRNA of A. veronii (Liu et al, 2015;Wang et al, 2019). SmpB also affects the transcription of sRNA and the tolerance to environmental stress (Wang et al, 2019).…”

“…As a transcription factor, SmpB participates in transcriptional regulation of bvgS and sRNA of A. veronii (Liu et al, 2015;Wang et al, 2019). SmpB also affects the transcription of sRNA and the tolerance to environmental stress (Wang et al, 2019). Analogously, tmRNA can act as sRNA and interact with crtMN mRNA to affect the synthesis of Staphylococcus aureus pigment (Liu et al, 2010).…”

Cbl upregulates cysH for hydrogen sulfide production in Aeromonas veronii

“…Previously smpB deletion exhibits more tolerance to aminoglycosides antibiotic and oxidative stress under M9 culture (Fig. 2C) (Liu et al, 2018;Wang et al, 2019). In summary, we proposed that Cbl-regulated H 2 S generation compensated for the resistance and survival of SmpB damage under nutrient deficiencies, contributing to the adaptation and evolution of Aeromonas veronii against extreme environment.…”

“…The DNA fragment including both cbl gene and its promoter was amplified by PCR (Wang et al, 2019). PCR reaction was performed as follow: 98 C for 2 min, stepped by 98 C for 30 s, 55 C for 30 s and 72 C for one kb/min in 30 cycles.…”

Hfq Regulates Efflux Pump Expression and Purine Metabolic Pathway to Increase Trimethoprim Resistance in Aeromonas veronii

“…Aeromonas veronii (A. veronii) is a rod-shaped gram-negative pathogen found in diseased grass fish, tilapia, and turtles. It can cause huge losses in the aquaculture industry but also infect humans ( Liu et al, 2015 ; Wang et al, 2019 ). A. veronii performs multiple drug resistance to antibiotics such as ampicillin, kanamycin, streptomycin, and gentamycin, resulting in the increased risk of human diseases and the greater losses to the fishery ( Liu et al, 2017 ; Wang et al, 2019 ; Zhang et al, 2019 ).…”