Differential scanning calorimetry of wholeEscherichia colitreated with the antimicrobial peptide MSI-78 indicate a multi-hit mechanism with ribosomes as a novel target

Abstract

Differential Scanning Calorimetry (DSC) of intact Escherichia coli (E. coli) was used to identify non-lipidic targets of the antimicrobial peptide (AMP) MSI-78. The DSC thermograms revealed that, in addition to its known lytic properties, MSI-78 also has a striking effect on ribosomes. MSI-78’s effect on DSC scans of bacteria was similar to that of kanamycin, an antibiotic drug known to target the 30S small ribosomal subunit. An in vitro transcription/translation assay helped confirm MSI-78’s targeting of ribosomes. The scrambled version of MSI-78 also affected the ribosome peak of the DSC scans, but required greater amounts of peptide to cause a similar effect to the unscrambled peptide. Furthermore, the effect of the scrambled peptide was not specific to the ribosomes; other regions of the DSC thermogram were also affected. These results suggest that MSI-78’s effects on E. coli are at least somewhat dependent on its particular structural features, rather than a sole function of its overall charge and hydrophobicity. When considered along with earlier work detailing MSI-78’s membrane lytic properties, it appears that MSI-78 operates via a multi-hit mechanism with multiple targets.

Mechanisms of Action for Antimicrobial Peptides With Antibacterial and Antibiofilm Functions

“…In this review, a number of examples that make use of biophysical methods to determine MOAs that involve DNA/RNA targets (Park et al, 1998;Hsu et al, 2005;Nam et al, 2014), protein targets (Mardirossian et al, 2014(Mardirossian et al, , 2018Krizsan et al, 2015), stringent response inhibition (de la Fuente-Núñez et al, 2014;Pletzer et al, 2017b), and degradation of biofilms (Segev-Zarko et al, 2015;Ansari et al, 2017) were presented. A number of examples of how these biophysical approaches can be applied to bacteria (i.e., termed "biological" assays here) (de la Fuente-Núñez et al, 2014;Brannan et al, 2015;Miyoshi et al, 2017;Overall et al, 2019) serve to illustrate not only how the lines between these methods may become increasingly blurred in the future, but also how all the methods presented in this review, as well as direct visualization approaches [e.g., scanning electron microscopy (SEM) (Chileveru et al, 2015)] and other new approaches [e.g., small angle X-ray scattering (Von Gundlach et al, 2016, von Gundlach et al, 2019], will continue to be relevant.…”

“…By using phospholipids with deuterated acyl chains, 2 H NMR can examine the effect of the HDP on acyl chain order (Marcotte et al, 2003). Recently, DSC has been used to probe the interaction of the AMP MSI-78 in whole bacteria (Brannan et al, 2015). Likewise, 31 P NMR studies on whole bacterial cells have also been reported (Overall et al, 2019).…”

Mechanistic and structural basis of bioengineered bovine Cathelicidin-5 with optimized therapeutic activity

“…8 (right panel). The membrane disruption and intracellular activities has also been seen in a well-studied α-helical peptide MSI-78383940. On the whole, the projected approach shade lights on the mechanistic and structural basis of bovine cathelicidin-5 interaction at the atomic level to develop therapies against multiple diseases.…”

“…The complete protocol for reaction mixture and final solution preparation was followed as described elsewhere38. Peptide concentration of 2, 10, 30, 60 and 100 μM were used for our analysis.…”

Antimicrobial Peptides — A Potential Replacement for Traditional Antibiotics

“…Их антимикробные свойства проявляются уже внутри клетки. Если одни пептиды связываются с отрицательно заряженными молекулами ДНК и РНК [67], другие блокируют активность рибосом [11]. В обоих случаях нарушается синтез белка, и клетка гибнет.…”