The Analogs of Temporin-GHa Exhibit a Broader Spectrum of Antimicrobial Activity and a Stronger Antibiofilm Potential against Staphylococcus aureus

Abstract

The abuse of antibiotics has led to the emergence of multidrug-resistant bacteria, which is becoming a serious worldwide problem people have to face. In our previous study, temporin-GHa (GHa) cloned from Hylarana guentheri showed antimicrobial activity against Gram-positive bacteria. In order to improve its therapeutic potential, we used a template-based and a database-assisted design to obtain three derived peptides by replacing the histidine at both ends of GHa with lysine, which exhibited faster and stronger bactericidal activity and a broader spectrum than the parent peptide. GHaK and GHa4K targeted to the bacterial membrane to exert their antibacterial activities at a faster membrane damage rate. The derived peptides inhibited the initial adhesion and the formation of Staphylococcus aureus biofilms, and eradicated the mature biofilms, which indicated that the derived peptides effectively penetrated the biofilm and killed bacteria. The therapeutic index (TI) and cell selectivity index (CSI) of the derived peptides increased significantly, which means a broader therapeutic window of the derived peptides. The derived peptides with improved activity and cell selectivity have the potential to be the promising candidates for the treatment of S. aureus infections. Our research also provides new insights into the design and development of antimicrobial peptides.

The Antimicrobial Peptide Temporin G: Anti-Biofilm, Anti-Persister Activities, and Potentiator Effect of Tobramycin Efficacy Against Staphylococcus aureus

“…Therefore, the search for alternative compounds to counteract S. aureus infections is in highly demand [ 39 , 40 ]. Temporins are a family of frog-skin AMPs whose various isoforms have already shown activity against Gram-positive bacteria [ 23 , 41 , 42 ]. For instance, TA has a MIC ranging from 4 to 16 µg/mL towards human methicillin-resistant S. aureus (MRSA) clinical isolates [ 18 ]; TB and different synthetic analogs inhibit the growth of various S. aureus strains alone or in combination with TA [ 22 , 43 ].…”

“…After 24 h of incubation, the minimum peptide concentration able to eradicate biofilm was equal to 64 mg/L. In another recent study conducted by Xie and coworkers, temporin–GHa cloned from Hylarana guenther was found to disrupt 90% of S. aureus biofilm biomass after 24 h of treatment at 100 µM [ 41 ]. A 24 h-long treatment of S. aureus biofilm with two different analogs of TB (at 30 µM) was investigated by Grassi and collaborators with ~1 log (90%) decrease in the number of viable biofilm cells [ 47 ].…”

Aggregation and Its Influence on the Bioactivities of a Novel Antimicrobial Peptide, Temporin-PF, and Its Analogues

“…Temporins often exhibited potent antimicrobial activity against the growth of Gram-positive bacteria, while the effect on Gram-negative bacteria is weaker [ 26 ]. The antimicrobial killing effect is generally recognized to permeabilize the cell membrane, resulting in the disruption of the structure [ 27 ].…”

“…Moreover, forming oligomers in some microenvironments, such as lipopolysaccharides (LPS) of Gram-negative bacteria, could escalate the difficulty for temporin to traverse the outer membrane, which weakens the antimicrobial activity on Gram-negative bacteria [ 30 , 33 ]. Therefore, structural modifications and engineering have been continuously implemented for temporins to improve the therapeutic index and efficacy [ 20 , 26 , 30 , 34 ].…”

Bioevaluation and Targeted Modification of Temporin-FL From the Skin Secretion of Dark-Spotted Frog (Pelophylax nigromaculatus)

“…The small temporins are inactive against most bacterial strains ( Simmaco et al, 1996 ), however, truncation of amino acids is widely applied for adjusting peptide physicochemical properties, including membrane affinity ( Feng et al, 2020 ; He et al, 2020 ; Zhu et al, 2020 ). According to previous studies, modification of temporins is always performed via amino acids alteration or terminal sequence addition ( Mangoni et al, 2011 ; Bezzerri et al, 2014 ; Xie et al, 2019 ), the rational truncation of selected amino acid residues is quite rare. In this study, two novel peptide derivatives were intentionally designed to investigate how the truncation of non-charged amino acids affects the bioactivity of small peptides.…”