An Efficient Approach for the Design and Synthesis of Antimicrobial Peptide-Peptide Nucleic Acid Conjugates.

Jian Li,Rong Li,Kade D Roberts,Jing Lu,Mohammad A K Azad,Nitin A Patil,Tony Velkov,Hasini Wickremasinghe,Kavya Pamulapati,Heidi H Yu,Varsha J Thombare,Xiaoji He

doi:10.3389/fchem.2022.843163

Abstract

Peptide-Peptide Nucleic Acid (PNA) conjugates targeting essential bacterial genes have shown significant potential in developing novel antisense antimicrobials. The majority of efforts in this area are focused on identifying different PNA targets and the selection of peptides to deliver the peptide-PNA conjugates to Gram-negative bacteria. Notably, the selection of a linkage strategy to form peptide-PNA conjugate plays an important role in the effective delivery of PNAs. Recently, a unique Cysteine- 2-Cyanoisonicotinamide (Cys-CINA) click chemistry has been employed for the synthesis of cyclic peptides. Considering the high selectivity of this chemistry, we investigated the efficiency of Cys-CINA conjugation to synthesize novel antimicrobial peptide-PNA conjugates. The PNA targeting acyl carrier protein gene (acpP), when conjugated to the membrane-active antimicrobial peptides (polymyxin), showed improvement in antimicrobial activity against multidrug-resistant Gram-negative Acinetobacter baumannii. Thus, indicating that the Cys-CINA conjugation is an effective strategy to link the antisense oligonucleotides with antimicrobial peptides. Therefore, the Cys-CINA conjugation opens an exciting prospect for antimicrobial drug development.

Highlights

IntroductionAntimicrobial resistance is considered one of the greatest threats to global health and the economy
In the present work we explore the utility of the Cys-commercially avaliable 2cyanoisonicotinamide (CINA) conjugation strategy for the generation of novel antimicrobial peptide-Peptide Nucleic Acid (PNA) conjugates
Intrigued by the activity of LASP-132 against polymyxinresistant A. baumannii isolates (5075R with LPS phosphoethanolamine modification, and LPS loss polymyxindependent resistant isolate 5075D), we investigated the potential mode of action of our PNA conjugates using flow cytometry (Figure 5)

Summary

Introduction

Antimicrobial resistance is considered one of the greatest threats to global health and the economy. The World Health Organization (WHO) identified multidrug-resistant (MDR) Gramnegative pathogens such as Pseudomonas aeruginosa, Acinetobacter baumannii, Enterobacterales as the top priority for the development of new antibiotics (WHO, 2017). This situation has been made even more problematic by the lack of development of new effective antibiotic drug therapies targeting these multi-drug resistant (MDR) bacteria. There is an urgent requirement for the development of antibiotics with novel modes of action (Andersson et al, 2016; WHO, 2017) To this end, antisense antibiotics such as Peptide Nucleic Acids (PNAs) can be used to target essential genes in bacteria, resulting in translational gene silencing and bactericidal effects (Good et al, 2001; Ghosal and Nielsen, 2012). PNAs are artificial DNA mimics with tertiary amide linked nucleobases

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