Fine-Tuning of Alkaline Residues on the Hydrophilic Face Provides a Non-toxic Cationic α-Helical Antimicrobial Peptide Against Antibiotic-Resistant ESKAPE Pathogens

Xudong Luo; Xiangdong Ye; Li Ding; Wen Zhu; Pengcheng Yi; Zhiwen Zhao; Huanhuan Gao; Zhan Shu; Shan Li; Ming Sang; Jue Wang; Weihua Zhong; Zongyun Chen

doi:10.3389/fmicb.2021.684591

Fine-Tuning of Alkaline Residues on the Hydrophilic Face Provides a Non-toxic Cationic α-Helical Antimicrobial Peptide Against Antibiotic-Resistant ESKAPE Pathogens

Front Microbiol. 2021 Jul 15:12:684591. doi: 10.3389/fmicb.2021.684591. eCollection 2021.

Authors

Xudong Luo^{1

2}, Xiangdong Ye^{1

2}, Li Ding^{1

3}, Wen Zhu¹, Pengcheng Yi¹, Zhiwen Zhao¹, Huanhuan Gao¹, Zhan Shu¹, Shan Li¹, Ming Sang⁴, Jue Wang¹, Weihua Zhong⁵, Zongyun Chen^{1

2}

Affiliations

¹ Institute of Biomedicine and Hubei Key Laboratory of Embryonic Stem Cell Research, College of Basic Medicine, Hubei University of Medicine, Shiyan, China.
² Hubei Key Laboratory of Wudang Local Chinese Medicine Research, Hubei University of Medicine, Shiyan, China.
³ Department of Clinical Laboratory, Dongfeng Hospital, Hubei University of Medicine, Shiyan, China.
⁴ Central Laboratory of Xiangyang No. 1 People's Hospital, Hubei University of Medicine, Shiyan, China.
⁵ Department of Rehabilitation Medicine, Taihe Hospital, Hubei University of Medicine, Shiyan, China.

Abstract

Antibiotic-resistant ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) has become a serious threat to public health worldwide. Cationic α-helical antimicrobial peptides (CαAMPs) have attracted much attention as promising solutions in post-antibiotic era. However, strong hemolytic activity and in vivo inefficacy have hindered their pharmaceutical development. Here, we attempt to address these obstacles by investigating BmKn2 and BmKn2-7, two scorpion-derived CαAMPs with the same hydrophobic face and a distinct hydrophilic face. Through structural comparison, mutant design and functional analyses, we found that while keeping the hydrophobic face unchanged, increasing the number of alkaline residues (i.e., Lys + Arg residues) on the hydrophilic face of BmKn2 reduces the hemolytic activity and broadens the antimicrobial spectrum. Strikingly, when keeping the total number of alkaline residues constant, increasing the number of Lys residues on the hydrophilic face of BmKn2-7 significantly reduces the hemolytic activity but does not influence the antimicrobial activity. BmKn2-7K, a mutant of BmKn2-7 in which all of the Arg residues on the hydrophilic face were replaced with Lys, showed the lowest hemolytic activity and potent antimicrobial activity against antibiotic-resistant ESKAPE pathogens. Moreover, in vivo experiments indicate that BmKn2-7K displays potent antimicrobial efficacy against both the penicillin-resistant S. aureus and the carbapenem- and multidrug-resistant A. baumannii, and is non-toxic at the antimicrobial dosages. Taken together, our work highlights the significant functional disparity of Lys vs Arg in the scorpion-derived antimicrobial peptide BmKn2-7, and provides a promising lead molecule for drug development against ESKAPE pathogens.

Keywords: ESKAPE pathogens; antibiotic resistance; cationic α-helical antimicrobial peptide; hemolytic activity; hydrophilic face; in vivo efficacy; lysine vs arginine.