Short Proline‐Rich Antimicrobial Peptides Inhibit Either the Bacterial 70S Ribosome or the Assembly of its Large 50S Subunit

Abstract

Short proline-rich antimicrobial peptides (PrAMPs) are a promising class of antibiotics that use novel mechanisms, thus offering the potential to overcome the health threat of multiresistant pathogens. The peptides bind to the bacterial 70S ribosome and can inhibit protein translation. We report that PrAMPs can be divided into two classes, with each class binding to a different site, and thus use different lethal mechanisms. Oncocin-type peptides inhibit protein translation in Escherichia coli by binding to the exit tunnel of the 70S ribosome with half maximal inhibitory concentrations (IC50 values) of around 2 to 6 μmol L(-1), whereas apidaecin-type peptides block the assembly of the large (50S) subunit of the ribosome, resulting in similar IC50 values. The revealed mechanisms should allow the design of new antibiotics to overcome current bacterial resistance mechanisms.

The Mechanism of Killing by the Proline-Rich Peptide Bac7(1–35) against Clinical Strains of Pseudomonas aeruginosa Differs from That against Other Gram-Negative Bacteria

“…Bac7 and its BODIPY fluorescently labeled derivative [Bac7 -BY] were prepared as previously described (14). Bac5(1-31) and BMAP27 (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18) were chemically synthesized as previously described (41). Apidaecin 137 and oncocin 112 were generously provided by Ralf Hoffmann (13,42).…”

“…All of them invariably have a high number of proline and arginine residues, show similar spectra of activity, including several Gram-negative species, and have similar modes of action. Recently different PR-AMPs, both mammalian Bac7 and insect oncocin and apidaecins, were demonstrated to efficiently bind to different regions of prokaryote ribosomes (9)(10)(11), leading to the inhibition of protein synthesis (12).…”

In vivo Efficacy and Pharmacokinetics of Optimized Apidaecin Analogs

“…This different in vitro behavior appears to be related to different inhibition mechanisms. Api137 disturbs the assembly of the 50S ribosomal subunit in E. coli leading to a protein complex size of around 42S (Krizsan et al, 2015b). This unique mode of action leads to high antimicrobial activities against E. coli ATCC 25922 (MIC = 4 μg/mL) and other Gram-negative bacteria.…”

Screening and Optimizing Antimicrobial Peptides by Using SPOT-Synthesis

“…Attacin is able to contribute to destabilization of the membrane of E. coli by preventing the transcription of the omp gene, thereby blocking the synthesis of important outer membrane proteins (Carlsson et al, 1991). It was also described that proline-rich peptides can bind the chaperon DnaK and the ribosome (Krizsan et al, 2015; Knappe et al, 2016a). Short AMPs can interact with ATP and inhibit ATP depended enzymes critical for the survival of the bacteria (Hilpert et al, 2010).…”