Poly-Arginine Tails and Helical Segments of Natural Antimicrobial Peptides Display Concerted Action at Membranes for Enhanced Antimicrobial Effects

Published

July 8, 2025

Author(s)

Navleen Kaur, Kinjal Mondal, Megan Mitchell, Sarala N. Padi, Jeffery B. Klauda, Antonio Cardone, Frank N. Heinrich, Christina Harris, David Giles, Mary Rooney, Erik Watkins, Myriam Cotten, David Hoogerheide, Mihaela Mihailescu

Abstract

Sequence motifs or patterns found in natural antimicrobial peptides (AMPs) have a great impact on their microbicidal activities. Here, through database inquiries and biological assays, we explore the enhanced antibacterial function associated with poly arginine (poly-R) motifs that typically occur as 3–5 concatenated R residues in many natural AMPs. Using a suite of biophysical techniques, we explore the structural consequences of a C-terminal poly-R motif at membranes and correlate our findings with the functional assays. We use natural peptides, such as Tilapia piscidin 4 (TP4), as an example of how various segments in an AMP play separate and synergistic roles to achieve unmatched bactericidal effects. The function of the poly-R segment is highly consequential since the simple addition of a five-arginine (R5) tail to an otherwise inert and weakly binding helical peptide creates a potent AMP. We investigate interactions of AMPs with lipid bilayers mimicking bacterial membrane compositions, including lipopolysaccharides, to show that the poly-R tail has a key role in initiating membrane destabilization through lipid segregation and water sequestration effects, all of which facilitate insertion and translocation of the amphipathic, α-helical N-terminal segment through the membrane. We compiled a large set of natural AMP sequences and MIC values to show that, statistically, the poly-R sequence motifs have, in average, a greater impact on the overall antimicrobial efficacy than equivalent sequences with poly-K motifs and similar charge densities. We discuss our observations in light of the unique structural and hydration properties of arginine residues.

Citation

ACS Bio & Med Chem Au

Volume

5

Issue

4

Pub Type

Journals

Download Paper

https://doi.org/10.1021/acsbiomedchemau.5c00084

Local Download

Keywords

antimicrobial peptide, poly-arginine, database, piscidin, MIC, lipid bilayer, X-ray, neutron reflectometry

Citation

Kaur, N. , Mondal, K. , Mitchell, M. , Padi, S. , Klauda, J. , Cardone, A. , Heinrich, F. , Harris, C. , Giles, D. , Rooney, M. , Watkins, E. , Cotten, M. , Hoogerheide, D. and Mihailescu, M. (2025), Poly-Arginine Tails and Helical Segments of Natural Antimicrobial Peptides Display Concerted Action at Membranes for Enhanced Antimicrobial Effects, ACS Bio & Med Chem Au, [online], https://doi.org/10.1021/acsbiomedchemau.5c00084, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=959727 (Accessed February 20, 2026)