Mode of Action of a Designed Antimicrobial Peptide: High Potency against Cryptococcus neoformans

Abstract

There is a significant need for developing compounds that kill Cryptococcus neoformans, the fungal pathogen that causes meningoencephalitis in immunocompromised individuals. Here, we report the mode of action of a designed antifungal peptide, VG16KRKP (VARGWKRKCPLFGKGG) against C. neoformans. It is shown that VG16KRKP kills fungal cells mainly through membrane compromise leading to efflux of ions and cell metabolites. Intracellular localization, inhibition of in vitro transcription, and DNA binding suggest a secondary mode of action for the peptide, hinting at possible intracellular targets. Atomistic structure of the peptide determined by NMR experiments on live C. neoformans cells reveals an amphipathic arrangement stabilized by hydrophobic interactions among A2, W5, and F12, a conventional folding pattern also known to play a major role in peptide-mediated Gram-negative bacterial killing, revealing the importance of this motif. These structural details in the context of live cell provide valuable insights into the design of potent peptides for effective treatment of human and plant fungal infections.

Structural insights into the combinatorial effects of antimicrobial peptides reveal a role of aromatic–aromatic interactions in antibacterial synergism

“…VG16KRKP and KYE28 individually are capable of forming membrane defects and killing cells by a detergent-like or toroidal-pore mechanism (29,30,68). As clearly demonstrated in this investigation, the VG16KRKP-KYE28 complex similarly destabilizes both bacterial cell walls and model membrane mimics.…”

“…Here, it should be noted that aromatic-aromatic interactions have been observed to be widely important for structural stabilization and hydrophobic domain formation in AMPs, e.g. the peptide combination used in this study, VG16KRKP and KYE28 as well as their shorter analogs, when present individually in LPS, exhibit similar structural characteristics (29,30,52,68). One should also note that previous work on AMP synergy has only partly succeeded in identifying structural features associated with synergy, which in turn has led to other approaches, such as that based on local curvature (62,64).…”

In Silico Approach for Prediction of Antifungal Peptides

“…We obtained peptides from different study performed by Datta et al (2016) , Li et al (2016) , and Garrigues et al (2017) . Therefore, to prevent biases we have taken peptides from different studies and checked the performance of our model on these peptides.…”

A Novel Antimicrobial Peptide Sparamosin26–54 From the Mud Crab Scylla paramamosain Showing Potent Antifungal Activity Against Cryptococcus neoformans

“…The effect of Sparamosin 26−54 on C. neoformans was observed using SEM as described earlier (Datta et al, 2016). Briefly, C. neoformans cells were harvested in the logarithmic phase and resuspended at approximately 1 × 10 7 cells/mL in NaPB, and incubated with 24 µM Sparamosin 26−54 at room temperature for 1 h. After incubation, the cells were fixed with 2.5% (vol/vol) glutaraldehyde at 4 • C for 2 h and washed three times before being placed on poly-L-lysine coated glass slides at 4 • C for 30 min.…”