14 research outputs found
Effects of Antimicrobial Peptide Revealed by Simulations: Translocation, Pore Formation, Membrane Corrugation and Euler Buckling
We explore the effects of the peripheral and transmembrane antimicrobial peptides on the lipid bilayer membrane by using the coarse grained Dissipative Particle Dynamics simulations. We study peptide/lipid membrane complexes by considering peptides with various structure, hydrophobicity and peptide/lipid interaction strength. The role of lipid/water interaction is also discussed. We discuss a rich variety of membrane morphological changes induced by peptides, such as pore formation, membrane corrugation and Euler buckling
Theoretical Insight into the Relationship between the Structures of Antimicrobial Peptides and Their Actions on Bacterial Membranes
Antimicrobial peptides with diverse
cationic charges, amphiphathicities,
and secondary structures possess a variety of antimicrobial activities
against bacteria, fungi, and other generalized targets. To illustrate
the relationship between the structures of these peptide and their
actions at microscopic level, we present systematic coarse-grained
dissipative particle dynamics simulations of eight types of antimicrobial
peptides with different secondary structures interacting with a lipid
bilayer membrane. We find that the peptides use multiple mechanisms
to exert their membrane-disruptive activities: A cationic charge is
essential for the peptides to selectively target negatively charged
bacterial membranes. This cationic charge is also responsible for
promoting electroporation. A significant hydrophobic portion is necessary
to disrupt the membrane through formation of a permeable pore or translocation.
Alternatively, the secondary structure and the corresponding rigidity
of the peptides determine the pore structure and the translocation
pathway
Nanodomain Formation of Ganglioside GM1 in Lipid Membrane: Effects of Cholera Toxin-Mediated Cross-Linking
Cross-linking of specific lipid components
by proteins mediates
transmembrane signaling and material transport. In this work, we conducted
coarse-grained simulation to investigate the interactions of binding
units of chorela toxin (CTB) with mixed ganglioside GM1 and dipalmitoylphosphatidylcholine
(DPPC) lipid bilayer membrane. We determine that the binding of CTB
pentamers cross-links GM1 molecules into protein-sized nanodomains
that have distinct lipid order compared with the bulk. The toxin in
the nanodomain partially penetrates into the membrane. The local disordering
can also transmit across the membrane via lipid coupling. Comparison
simulations on CTB binding to a membrane that is composed of various
lipid components demonstrate that several factors are responsible
for the nanodomain formation: (a) the negatively charged headgroup
of a GM1 receptor is responsible for the multivalent binding; (b)
the head groups being full of hydrogen-bonding donors and receptors
stabilize the GM1 cluster itself and ensure the toxin binding with
high affinity; and (c) significant size and order differences between
the protein receptor lipids and bulk lipids are essential to promoting
phase separation and signal transportation
A Mixture of Formic Acid, Benzoic Acid, and Essential Oils Enhanced Growth Performance via Modulating Nutrient Uptake, Mitochondrion Metabolism, and Immunomodulation in Weaned Piglets
This study aimed to evaluate the effects of a complex comprising formic acid, benzoic acid, and essential oils (AO3) on the growth performance of weaned piglets and explore the underlying mechanism. Dietary AO3 supplementation significantly enhanced the average daily gain (ADG) and average daily feed intake (ADFI), while decreasing the feed conversion rate (FCR) and diarrhea rate (p p < 0.05) compared with those piglets subjected to LPS. Furthermore, AO3 supplementation significantly ameliorated redox disturbances (T-AOC, SOD, and GSH) and inflammation (TNF-α, IL-1β, IL-6, and IL-12) in both the serum and jejunum of piglets induced by LPS, accompanied by suppressed activation of the MAPK signaling pathway (ERK, JNK, P38) and NF-κB. The LPS challenge downregulated the activation of the AMPK signaling pathway, mRNA levels of electron transport chain complexes, and key enzymes involved in ATP synthesis, which were significantly restored by the AO3 supplementation. Additionally, AO3 supplementation restored the reduced transport of amino acids, glucose, and fatty acids induced by LPS back to the levels observed in the control group. In conclusion, dietary AO3 supplementation positively affected growth performance and gut microbiota composition, also enhancing intestinal barrier integrity, nutrient uptake, and energy metabolism, as well as alleviating oxidative stress and inflammation under LPS stimulation