In vitro and in silico studies on membrane interactions of diverse Capsicum annuum flower γ‐thionin peptides

Abstract

Thionins are small, cysteine‐rich peptides that play an important role in plant defense, primarily through their interactions with membranes. Eight novel γ‐thionin peptides (CanThio1‐8) were isolated from the flower of Capsicum annuum. Sequence analysis revealed that the peptides cluster into three groups. A representative peptide from each group (CanThio1, 2, and 3) was used for experimental characterization. Interestingly, peptides were found to possess some cytotoxic activity against normal human embryonic kidney cell line but higher cytotoxicity against cancer cell line MCF‐7. CanThio3 peptide was chosen as a representative peptide to study the molecular mechanism of action on membranes. Microsecond timescale atomistic simulations of CanThio3 were performed in the presence of a POPC (1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine) lipid bilayer. Simulations revealed that CanThio3 interacts with the bilayer and causes lipid thinning in the vicinity. Nonpolar amino acids specific to the α‐core region of CanThio3 along with nonpolar residues in the γ‐core region are seen to interact with the lipid tails. The differences in the amino acid sequence of CanThio peptides in these regions explain the variability in cytotoxic activities. In summary, our results demonstrate the membrane‐mediated activity of a novel series of γ‐thionin peptides from C. annuum.

Proteinaceous α-amylase inhibitors: purification, detection methods, types and mechanisms

“…The α-core structure is a loop comprising the first β chain and the helix, while the γ-core structure is an area comprising the hairpin loop and it connects the second and third β-chains . [50,69] In one study, it was found that cowpea's plant defense protein VuD1 binds to the active site of amylase mainly through an N-terminal structure. Lys1 is obtained from VuD1, while Asp240 is obtained from Z.subfasciatus α-amylase (ZSA).…”

Proteins, Small Peptides and Other Signaling Molecules Identified as Inconspicuous but Possibly Important Players in Microspores Reprogramming Toward Embryogenesis

“…Plant γ -thionins can occur in all tissues including the female gametophyte, flowers, pollen, shoots, cotyledons, leaves, roots, bark, the endosperm of immature kernels and fruits. Their functional roles depend on the specific interactions with the plasma membrane (reviewed by Gomes, 2009, 2011;De Coninck and De Smet, 2016;Nikte et al, 2020). Several plant γ -thionins have been shown to induce the accumulation of intracellular ROS and to initiate PCD that are part of regulatory cascades leading to the protection or tolerance against pathogens (Hegedüs and Marx, 2013).…”

RecJf exonuclease-assisted signal amplification for the sensitive detection of di(2-ethylhexyl)phthalate by a Pd@Au NB labeled electrochemical aptasensor based on Au@Ni-CoHNB/PEI-g-C3N4

“…40,41 Gold-palladium core-shell nanobones (Pd@Au NBs) with larger specific surface area than gold nanorods (AuNRs) can be used as a carrier for immobilizing DNA strands and binding numerous Thi by Au-N bonds and Pd-N bonds. [42][43][44] Therefore, Thi-labeled Pd@Au NBs were synthesized as signal probes to reflect the signal changes generated by the recognition process.…”