Peptide Aptamer PA3 Attenuates the Viability of Aeromonas veronii by Hindering of Small Protein B-Outer Membrane Protein A Signal Pathway

Abstract

The small protein B (SmpB), previously acting as a ribosome rescue factor for translation quality control, is required for cell viability in bacteria. Here, our study reveals that SmpB possesses new function which regulates the expression of outer membrane protein A (ompA) gene as a transcription factor in Aeromonas veronii. The deletion of SmpB caused the lower transcription expression of ompA by Quantitative Real-Time PCR (qPCR). Electrophoretic mobility shift assay (EMSA) and DNase I Footprinting verified that the SmpB bound at the regions of −46 to −28 bp, −18 to +4 bp, +21 to +31 bp, and +48 to +59 bp of the predicted ompA promoter (PompA). The key sites C52AT was further identified to interact with SmpB when PompA was fused with enhanced green fluorescent protein (EGFP) and co-transformed with SmpB expression vector for the fluorescence detection, and the result was further confirmed in microscale thermophoresis (MST) assays. Besides, the amino acid sites G11S, F26I, and K152 in SmpB were the key sites for binding to PompA. In order to further develop peptide antimicrobial agents, the peptide aptamer PA3 was screened from the peptide aptamer (PA) library by bacterial two-hybrid method. The drug sensitivity test showed that PA3 effectively inhibited the growth of A. veronii. In summary, these results demonstrated that OmpA was a good drug target for A. veronii, which was regulated by the SmpB protein and the selected peptide aptamer PA3 interacted with OmpA protein to disable SmpB-OmpA signal pathway and inhibited A. veronii, suggesting that it could be used as an antimicrobial agent for the prevention and treatment of pathogens.

Outer Membrane Porins Contribute to Antimicrobial Resistance in Gram-Negative Bacteria

“… Schematic representation of the OmpA regulation pathways. The promoter of OmpA could be combined by SmpB [ 45 ] and an anti-(H-NS) repressor of A1S_0316 [ 46 ]. In Stenotrophomonas maltophilia , OmpA participates in the β-lactam resistance response through the sigma (P)-NagA-L1/L2 regulatory circuit [ 47 ].…”

“…Eight-stranded antiparallel β-barrel [108] Amikacin, novobiocin, cephalothin, sulfonamides, gentamicin, and nalidixic acid [80]; tetracycline, ciprofloxacin, chloramphenicol, lincomycin, rifampicin, aminoglycosides (kanamycin and streptomycin), and β-lactam (ampicillin, carbenicillin, ceftazidime, and imipenem) [110]; and β-lactam [111]. The promoter of OmpA could be combined by SmpB [45] and an anti-(H-NS) repressor of A1S_0316 [46]. In Stenotrophomonas maltophilia, OmpA participates in the β-lactam resistance response through the sigma (P)-NagA-L1/L2 regulatory circuit [47].…”

“…The expression of OmpA can be regulated by several genes ( Figure 1 ). In Aeromonas veronii , the lower transcription expression of ompA could be caused by the deletion of small protein B (SmpB) and four regions (−46 to −28 bp, −18 to +4 bp, +21 to +31 bp, and +48 to +59 bp) of the OmpA promoter combined by SmpB, which suggests that the SmpB protein was positively responsible for controlling OmpA expression at the stationary stage [ 45 ]. In A. baumannii , A1S_0316 displayed a higher affinity for binding to the OmpA promotor region than the global repressor H-NS, and it operates as an anti-repressor on the OmpA promotor region by preventing the binding of the AbH-NS protein [ 46 ].…”

Advances in screening, synthesis, modification, and biomedical applications of peptides and peptide aptamers

“…cubense‐induced banana wilt disease, thus providing a potential antifungal agent for disease management. Liu et al 186 elucidated a novel mechanism governing the expression of a transcription factor in Aeromonas veronii , mediated by the small protein B regulation of outer membrane protein A (ompA). Using bacterial two‐hybrid screening, they identified PA PA3 for ompA and confirmed its growth‐inhibitory effect on A. veronii through drug sensitivity tests, suggesting its potential as an antibacterial agent for A. veronii pathogens.…”