The peculiar N- and C-termini of trichogin GA IV are needed for membrane interaction and human cell death induction at doses lacking antibiotic activity

Abstract

Peptaibiotics, non-ribosomally synthetized peptides from various ascomycetes, are uniquely characterized by dialkylated a-amino acids, a rigid heli cal conformation, and membrane permeation properties. Although generally considered as antimicrobial peptides, peptaibiotics may display other toxicological properties, and their function is in many cases unknown. With the goal to define the biological activity and selectivity of the peptaibiotictrichogin GA IV from the human opportunist Trichodenna longibrachiatum we analyzed its membrane interaction,cytotoxic activity and antibacterial effect. Trichogin GA IV effectively killed several types of healthy and neoplastic human cells at doses (EC 50%= 4-6 ~) lacking antibiotic effects on both Gram- and Gram+ bacteria(MIC > 64 ~ ). The peptaibiotic distinctive (-terminal primary alcohol was found to cooperate with theN-terminal n-octanoyl group to permeate the membrane phospholipid bilayer and to mediate effective binding and active endocytosis of trichogin GA IV in eukaryotic cells, two steps essential for cell death induction.Replacement of one Gly with Lys plus the simultaneous esterification of the (-terminus, strongly increased trichogin GA IV anti-Gram+ activity (MIC 1-4 ~ ). but further mitigated its cytotoxicity on human cells.

Comparison of bactericidal and cytotoxic activities of trichogin analogs

“…When a fatty acid chain (of 8–10 carbon atoms) is present at their N-terminus, they are called lipopeptaibols (Toniolo et al, 2001; Degenkolb et al, 2003) [4] , [5] . We found (Tavano et al, 2015) [6] that the lipopeptaibol trichogin displays no antibacterial effects up to 64 µM, against both Gram − and Gram + bacteria, but kills tumor and healthy human cells via a mechanism requiring both the C-terminal primary alcohol group and the N-terminal n-octanoyl moiety, with EC50s around 4–5 µM. However, the substitution of single Gly residues with Lys strongly improves anti-Gram + activity (Tavano et al, 2015; De Zotti, Biondi, Park et al, 2012; De Zotti, Biondi, Peggion et al, 2012) [6] , [7] , [8] .…”

Targeted Amino Acid Substitutions in a Trichoderma Peptaibol Confer Activity against Fungal Plant Pathogens and Protect Host Tissues from Botrytis cinerea Infection

“…The presence of a lipophilic acyl chain at the N-terminus makes trichogin a lipo peptaibol [ 28 ] and has been associated with inhibition of plant-pathogenic bacteria and fungi [ 29 ]. This helical, mostly hydrophobic, 11-residue peptaibol is naturally produced by T. longibrachiatum , and its activity has been assayed in various biological systems [ 26 , 30 , 31 ]. In this manuscript, we describe the synthesis, conformational analysis, proteolytic resistance, and fungicidal activity of water-soluble, cationic analogs of trichogin ( Table 1 ).…”

“…In this manuscript, we describe the synthesis, conformational analysis, proteolytic resistance, and fungicidal activity of water-soluble, cationic analogs of trichogin ( Table 1 ). Some of the analogs synthesized and tested in the present work were chosen in light of the promising results obtained for them in previous studies involving human bacterial pathogens [ 30 , 32 ]. Cationic peptides have been previously found to be effective against fungal plant pathogens [ 33 , 34 ].…”

Isolation and Total Synthesis of Albu­peptins A–D: 11‐Residue Peptaibols from the Fungus Gliocladium album

“…of biological and pharmacological properties, including antibiotic, [18,19] antiviral, [20,21] neuroleptic, [22,23] cytotoxic, [24,25] antiparasitic, [24,26] and antifungal [27,28] activities. As part of ongoing screening studies for new biologically active metabolites based on our highly diverse fungal strain collection, we found that the culture extract of Gliocladium album (Preuss) Petch significantly inhibited the growth of various phytopathogenic organisms.…”