Biochemistry (Moscow), Supplement Series A: Membrane and Cell Biology最新文献

The voltage-gated potassium ion channel KCNQ1 has physiological importance in modulation of electrical excitability in cardiac and epithelial cells. Its activity is modulated by certain proteins or small molecules and its dysfunction may result in arrhythmia, increasing risk of sudden death. Recent research has revealed that Mallotoxin (MTX), a bioactive compound derived from the plant Mallotus philippensis enhances the current generated by the KCNQ1–KCNE1 complex while exerting a modest inhibitory effect on the KCNQ1–KCNE3 channel. The molecular mechanisms underlying these contrasting effects remain unclear, given the structural similarities between the KCNE1 and KCNE3 subunits in their transmembrane regions. Therefore, we employed homology modeling to reconstruct a structural model of the KCNQ1–KCNE1 complex based on the cryo-EM structure of the KCNQ1–KCNE3 complex. Computational analyses of the electrostatic potential landscapes revealed significant differences between these complexes, with the KCNQ1–KCNE3 complex exhibiting a unique region of positive electrostatic potential located centrally within the channel, a feature absent in the KCNQ1–KCNE1 complex. Considering that MTX displays negative charge at physiological pH, we propose that MTX preferentially interacts with this positively charged domain in the KCNQ1–KCNE3 channel, leading to ion flow inhibition, which was supported by further molecular docking observation. Moreover, molecular docking studies suggest that MTX augments the activity of the KCNQ1–KCNE1 complex by stabilizing its open-state structure. These findings clarify the dual modulatory role of MTX in the KCNQ1–KCNE complex and advance therapeutic design for ion channelopathies.

In this work we aimed to investigate in silico the influence of the common experimental factors on the determination of the oligomerization parameter in the quantitative photoactivated localization microscopy (qPALM). qPALM exploits statistical characteristics of the clusters of individual blinks to deduce the oligomerization of the labeled protein. The aim of this work is to investigate how the properties of the label (number of blinks before photobleaching and fraction of incorrectly folded protein), protein surface density and impurities on the surface may influence the determination of the dimerization fraction. To achieve this, we synthesize sets of image series in different conditions, process them using common protocol, and compare the true and obtained dimerization fraction.

Parkinson’s disease is a neurodegenerative disease associated with the destruction of motor neurons. One of the biomarkers of the disease is Levy’s bodies, consisting mainly of α-synuclein protein. The protein forms aggregates, the mechanism of formation of which is still not fully understood. We propose a method for modeling protein–protein interaction by combining classical molecular dynamics methods and the Landau–Ginzburg–Wilson approach. The energy of the single protein chain is represented by the modernized Hamiltonian of the Abelian Higgs model. Interactions between different protein chains are taken into account due to the modernized Lennard–Jones potential and the Debye–Huckel potential. Two structures of α-synuclein were taken for the study: a micelle monomer and one of the tetramer molecules. Our results reveal that molecules derived from tetramers show a predisposition to form aggregates, while originally single molecules do not exhibit this tendency.

This paper analyzes the structural and functional organization of mitochondria. It is shown that deformation of membrane lipids by supercomplexes of the mitochondrial respiratory chain and ATP synthase dimers leads to their mutual attraction. It has been shown that membrane bending near the proton pump creates a dedicated direction for the movement of protons to ATP synthase. Mitochondria can operate in the standby mode with loose coupling but also with low oxidative damage. They can switch to the mode of tight coupling and clustering of oxidative phosphorylation system (OXPHOS) at high energy demand conditions due to the changes in ultrastructure.

The complement system is an important part of the immune system that controls the body’s defense against pathogens. One of the pro-inflammatory active components of the system is the proteolytic fragment C3a, which primarily acts through the corresponding receptor C3aR, promoting both the physiological response and in case excessive downstream activation contributes to the development of a wide range of disorders of predominantly inflammatory etiology. Studies on animal models have highlighted the potential of C3aR as an important drug target. The present work describes the generation of genetic constructs for expression of the C3aR receptor in the insect cell line S f 9, purification and characterization of C3aR for further structural and functional studies. We anticipate that this work will contribute to the determination of the receptor structure by X-ray crystallography and lead to rational drug design for treating inflammation disorders.

Migraine is a widespread disorder which is defined by persistent and recurring headache attacks. Trigeminal-vascular system (TVS), including meningeal afferents of trigeminal ganglion, is considered to be a key structure in generating nociceptive signals in migraine, in which dopaminergic and trace amine-mediated effects remain unexplored. DAT-HET rats, heterozygous of DAT-KO line, provide a useful model for studying the role of moderate changes in DA homeostasis in migraine mechanisms. In this research, we investigated tyramine and dopamine (DA) effects in trigeminal peripheral afferents with elecrophysiological recording of action potentials of the trigeminal nerve in the rat hemiskull preparations. The data obtained indicates that DA application exerts pro-nociceptive action in trigeminal meningeal afferents in both WT (wild type) and DAT-HET groups in similar manner. Tyramine application also exhibited pro-nociceptive action in peripheral afferents, but demonstrated prolonged pro-nociceptive effect in DAT-HET group. Our data contributes to understanding of dopaminergic signaling in TVS by functionally confirming interplay between dopaminergic system and trace amines in peripheral afferents; as well as by demonstrating of novel electrophysiological evidence of tyramine pro-nociceptive action in TVS.

Migraine is a common chronic neurovascular disease accompanied by unilateral headache, photophobia, allodynia, and autonomic disturbances. About 1/3 of migraine patients have a transient neurological deficit that precedes or overlaps the headache phase, called aura. The main physiological mechanism underlying aura is thought to be cortical spreading depression (CSD), a wave of massive depolarization passing through neurons and glial cells of the cortex. The aim of the present study was to develop the model of chronic migraine with aura in rats and analyze the main behavioral and biochemical correlates of migraine. Male rats were subjected to surgery with the installation of a mini bath providing access to the dura mater above the somatosensory cortex. KCl was applied on the dura mater to induce CSD every other day for 9 days. Sham rats obtained NaCl application according to the same protocol. Behavioral tests were performed before and after application of KCl or NaCl. Repeated KCl application decreased locomotor and exploratory activity, as well as cognitive ability, increased anxiety and induced photophobia and allodynia in rats. Besides, rats with a model of chronic migraine with aura showed increased plasma calcitonin gene-related peptide (CGRP) concentration and decreased glutathione peroxidase activity in brain tissue. In conclusion, the proposed model can be used to study the behavioral correlates of chronic migraine with aura in experimental animals, which will allow us to investigate the underlying mechanisms and develop treatment approaches.

Ferritin is an iron-storage protein complex performing vital functions in various living organisms. Its properties are significantly defined by a topology of the protein globule and the structural arrangement of subunits on its surface. Understanding the mechanisms of ferritin self-assembly could open up new ways of functionalization of its surface coating with a number of applications in biotechnology. In this study, we investigated the self-assembly of ferritin using the Smoluchowski coagulation model. We numerically solved the Smoluchowski differential equations for various models, involving the formation of hybrid ferritins with two types of subunits (for instance, H and L). Our model incorporates different reaction schemes and provides insights into the kinetics of oligomer assembly. The results reveal that our model can accurately describe the temporal dynamics of ferritin assembly, predicting the formation of intermediate states and fully assembled globules. The extension of the model using a four-dimensional coagulation kernel enables a detailed description of hybrid ferritin assembly, offering a new perspective on the complexity of self-assembly processes in heterooligomeric protein systems. Overall, our findings provide a robust framework for understanding the dynamics of ferritin assembly, offering insights that could be generalized to other carriers and help in designing more effective experimental approaches to study these mechanisms.

The hybrid shell@core nanosystem Cy5-HSA@IONPs containing magnetic iron oxide core and Cy5-HSA shell was engineered and characterized by composition, stability and integrity using fluorescent measurements, UV/Vis-spectrophotometry (particularly, Bradford protein assay), dynamic light scattering, electron magnetic resonance in solution, in cells and cell lysates. Conjugation of HSA to Cyanine 5 (Cy5) fluorescent dye was carried out for qualitative and quantitative estimations. The research included incubation of hybrid nanosystems with human adenocarcinoma cells (HCT116 and MCF7, colon and breast cell lines, respectively) followed by cell lysis, magnetic separation and quantitative determination of protein on the surface of the magnetic cores after mild cell lysis and in suspension of cell residues. The presence of the albumin coating on the surface of magnetic cores (IONPs) upon delivery to the cells has been proven and the effectiveness of the engineered hybrid particles as a drug (photosensitizer) delivery platform has been discussed.

Loss of macroautophagy and loss of proteostasis are hallmarks of aging. Lysosomal dysfunction is one of the reasons for the accumulation of non-degradable defective macromolecules, protein aggregates, and damaged organelles in the cells of organisms. The summary of experimental data obtained so far indicates an age-dependent weakening of lysosomal function. We hypothesize that lysosomes, as part of the autophagy and signaling network, are of great importance for longevity. In this review, we summarize information on the mechanisms of lysosomal influence on the lifespan and existing approaches to stimulate lysosomal function for longevity. We emphasize that factors such as intraluminal pH and interactions of lysosome-associated regulatory proteins (mTOR, AMPK, TFEB, and others) are related to aging. Stimulation of lysosomal function by dietary restriction, pharmacological or optogenetic approaches could be one of the promising interventions for anti-aging protection. In particular, a novel group of lysosomal optogenetic tools with high specificity of action could be a breakthrough in aging research.