Design of a novel antimicrobial peptide 1018M targeted ppGpp to inhibit MRSA biofilm formation

Abstract

Methicillin-resistant staphylococcus aureus (MRSA) and its biofilm infection were considered as one of the main international health issues. There are still many challenges for treatment using traditional antibiotics. In this study, a mutant peptide of innate defense regulator (IDR-)1018 named 1018M was designed based on molecular docking and amino acid substitution technology. The antibacterial/biofilm activity and mechanisms against MRSA of 1018M were investigated for the first time. The minimum inhibitory concentration (MIC) of 1018M was reduced 1 time (MIC = 2 μg/mL) compared to IDR-1018. After treatment with 32 μg/mL 1018M for 24 h, the percentage of biofilm decreased by 78.9%, which was more effective than the parental peptide. The results of mechanisms exploration showed that 1018M was more potent than IDR-1018 at destructing bacterial cell wall, permeating cell membrane (20.4%–50.1% vs 1.45%–10.6%) and binding to stringent response signaling molecule ppGpp (increased 27.9%). Additionally, the peptides could also exert their activity by disrupting genomic DNA, regulating the expression of ppGpp metabolism and biofilm forming related genes (RSH, relP, relQ, rsbU, sigB, spA, codY, agrA and icaD). Moreover, the higher temperature, pH and pepsase stabilities provide 1018M better processing, storage and internal environmental tolerance. These data indicated that 1018M may be a potential candidate peptide for the treatment of MRSA and its biofilm infections.

Novel Hybrid Peptide Cathelicidin 2 (1-13)-Thymopentin (TP5) and Its Derived Peptides with Effective Antibacterial, Antibiofilm, and Anti-Adhesion Activities

“…In our study, the transcriptional levels of genes (agrA, sigB, and lrgB) in CTPstreated biofilms were not significantly different, which might prove that the antibiofilm activity of CTPs mainly relied on membrane destruction, instead of the regulation of gene expression (Figure 12). However, these results may differ from Jiale's report that AMP 1018 M could display both disruption of the cell membrane and modulation of biofilmassociated gene expression, which might be due to the target of 1018 M function being ppGpp, a stringent response signaling molecule that regulates the expression of many biofilm-formation-relevant genes [49]. As shown in Figure 14, we speculated on the mechanisms of antibacterial and antibiofilm effects of CTPs against S. aureus ATCC 43300 in the hypothesized model.…”

“…All of the CTPs exhibited significant antibiofilm activity and could effectively inhibit biofilm formation of most tested S. aureus strains at sublethal concentrations (1 × MIC), as detected using the crystal violet method (Figure 9). This was consistent with other reports, which suggest that membrane-penetrated peptides may also block the formation of pathogen biofilms [49,50]. C-terminal amidation of the peptides has been reported to enhance its antibiofilm activity [51].…”

“…We simultaneously analyzed the transcriptional levels of biofilm-related genes in S. aureus ATCC 43300 by qRT-PCR. An important gene in the Agr QS system of S. aureus, agrA, can regulate the behavior of the entire population [49,52]. Furthermore, sigB expression down-regulates protease production, but promotes the expression of adhesion factors, which contributes to the initial formation of biofilms [53].…”

Prospection and prediction of highly active antibiofilm peptides using machine learning-based methods

“…1018M inhibited biofilm formation, but IDR-1018 did not affect biofilm formation. 1018M's hydrophobicity is significantly less than IDR-1018, and its hydrophobic ratio was 25% less than IDR-1018 [52]. In Fig.…”

Effect and Mechanisms of Antibacterial Peptide Fraction from Mucus of C. aspersum against Escherichia coli NBIMCC 8785

“…The morphological parameters of the cell were changed, and the metabolic activity was inhibited at a very high level. When studying the opportunities for the achievement of the desired effect in newly arisen infections through a decrease in the concentration of the peptide fraction but with an increase in the exposition time, we found that the 10% peptide fraction led to the achievement of the desired effectdamage to the structures and functions of the bacteria [65][66][67]. This led to a decrease in the fluorescence as a result of the blocking of the oxide reductase apparatus of the cells, and accumulation of degenerative bacterial cells, which were shortened and round, and had highly damaged surfaces.…”