The Dietary Nutrient Trimethylamine N-Oxide Affects the Phospholipid Vesicle Membrane: Probable Route to Adverse Intake

Interactions between Lipid Vesicle Membranes and Single Amino Acid Fibrils: Probable Origin of Specific Neurological Disorders

Amyloid fibrils are known to be responsible for several neurological disorders, like Alzheimer's disease (AD), Parkinson's disease (PD), etc. For decades, mostly proteins and peptide-based amyloid fibrils have been focused on, and the topic has acknowledged the rise, development, understanding of, and controversy, as well. However, the single amino acid based amyloid fibrils, responsible for several disorders, such as phenylketonuria, tyrosenimia type II, hypermethioninemia, etc., have gotten scientific attention lately. To understand the molecular level pathogenesis of such disorders originated due to the accumulation of single amino acid-based amyloid fibrils, interaction of these fibrils with phospholipid vesicle membranes is found to be an excellent cell-free in vitro setup. Based on such an in vitro setup, these fibrils show a generic mechanism of membrane insertion driven by electrostatic and hydrophobic effects inside the membrane that reduces the integral rigidity of the membrane. Alteration of such fundamental properties of the membrane, therefore, might be referred to as one of the prime pathological factors for the development of these neurological disorders. Hence, such interactions must be investigated in cellular and intracellular compartments to design suitable therapeutic modulators against fibrils.

A Mechanoelastic Glimpse on Hyaluronan-Coated Extracellular Vesicles

Cancer cells secrete extracellular vesicles (EVs) covered with a carbohydrate polymer, hyaluronan (HA), linked to tumor malignancy. Herein, we have unravelled the contour lengths of HA on a single cancer cell-derived EV surface using single-molecule force spectroscopy (SMFS), which divulges the presence of low molecular weight HA (LMW-HA < 200 kDa). We also discovered that these LMW-HA-EVs are significantly more elastic than the normal cell-derived EVs. This intrinsic elasticity of cancer EVs could be directly allied to the LMW-HA abundance and associated labile water network on EV surface as revealed by correlative SMFS, hydration dynamics with fluorescence spectroscopy, and molecular dynamics simulations. This method emerges as a molecular biosensor of the cancer microenvironment.

Amyloids Formed by Nonaromatic Amino Acid Methionine and Its Cross with Phenylalanine Significantly Affects Phospholipid Vesicle Membrane: An Insight into Hypermethioninemia Disorder

The incorrect metabolic breakdown of the nonaromatic amino acid methionine (Met) leads to the disorder called hypermethioninemia via an unknown mechanism. To understand the molecular level pathogenesis of this disorder, we prepared a DMPC lipid membrane, the mimicking setup of the cell membrane, and explored the effect of the millimolar level of Met on it. We found that Met forms toxic fibrillar aggregates that disrupt the rigidity of the membrane bilayer, and increases the dynamic response of water molecules surrounding the membrane as well as the heterogeneity of the membrane. Such aggregates strongly deform red blood cells. This opens the requirement to consider therapeutic antagonists either to resist or to inhibit the toxic amyloid aggregates against hypermethioninemia. Moreover, such disrupting effect on membrane bilayer and cytotoxicity along with deformation effect on RBC by the cross amyloids of Met and Phenylalanine (Phe) was found to be most virulent. This exclusive observation of the enhanced virulent effect of the cross amyloids is expected to be an informative asset to explain the coexistence of two amyloid disorders.