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

Controlled formation of through pores in bilayer lipid membranes is a key stage of various biotechnological techniques. Excess energy of the pore edge is characterized by line tension, the value of which determines the overall stability of the membrane with respect to pore formation. The practically important pore size is on the order of a few nanometers. It is impossible to study such pores by direct optical methods, but they can, in principle, be visualized by atomic force microscopy. This method uses a solid support on which the lipid bilayer is held due to the interaction of one of the monolayers with it. In this work, we theoretically investigated the effect of the presence of the support on the value of the line tension of the pore edge. It was assumed that the line tension is determined by the energy of elastic deformation of the membrane at the edge. Various regimes of membrane interaction with the support were considered: from a free-standing membrane (complete absence of interaction) to the case of infinitely strong adhesion of the membrane to the support. The calculation results show that the relative change in the line tension of the pore edge within such variation of the intensity of the interaction of the membrane with the support is less than 3.5%. Thus, the developed theoretical model predicts an extremely weak effect of the interaction with the support on the magnitude of the line tension–the main energy characteristic of the pore edge.

Specific patterns of lipid distribution in cell membranes determine their structural and signaling roles and ensure the integrity and functionality of the plasma membrane and cell organelles. Recent advances in the development of recombinant lipid biosensors and imaging techniques allow direct observation of the distribution, movement, and dynamics of lipids within cells, significantly expanding the understanding of lipid functions and their involvement in cellular and subcellular processes. In this review, we summarize the data related to the development and application of recombinant protein sensors for various lipids in cell membranes.

During cellular metabolism, reactive oxygen species and nitrogen species are produced which inherently results in oxidative damage of DNA and proteins. As a survival mechanism, these stressors modulate gene expression and various signalling pathways in C. elegans. The resistance to various forms of stress peaks in early adulthood and thereafter, decreases with age. In C. elegans, the gene aak-2 enables the adenosine monophosphate (AMP)-activated protein kinase activity which is involved in stress responses, germ cell cycle arrest during dauer formation, and maintenance of longevity. In this study, we evaluated the effects of mangiferin (MF) and trans-cinnamic acid (TCA) at concentrations of 10, 50, 100, and 200 µM on the survival rate, lifespan, and motility of C. elegans treated with hydrogen peroxide. The nematodes (wild type N2-Bristol and aak-2 mutant strains) were exposed to oxidative stress and then observed for the computation of percentage of survival (survival rate), motility, and maximum lifespan (ML). Treatment of wild-type C. elegans exposed to oxidative stress with TCA at concentrations of 50, 100, and 200 μM significantly (p < 0.05) increased the survival rate and ML of nematodes compared to the control. Furthermore, MF at all doses studied significantly (p < 0.05) increased the survival rate and extended the life span of H₂O₂-stressed wild-type nematodes fourfold. In the aak-2 mutant strain, the survival rate and ML were only increased in the nematodes treated with 100 and 200 µM of TCA. There was also a dose-dependent increase in survival rate and ML of nematodes treated with MF. MF at the concentration of 200 µM prolonged the lifespan of nematodes by 5 days and restored motility function in 30% of the total nematode population.

We present the results of the study of the structural distinctions between the purple membrane (PM) of Halobacterium salinarum and the claret membrane (CM) of Haloquadratum walsbyi using small-angle and wide-angle X-ray scattering. PM and CM are rhodopsin-rich membrane regions. They are crucial for light-driven energy processes in extreme halophilic archaea. While PM structure has been extensively characterized, the structure of CM remains less understood. According to our data, PM exhibits a well-defined hexagonal crystalline lattice with unit cell parameters of a = b ≈ 62 Å, which is consistent with published data. Conversely, CM showed unexpected diffraction patterns, best fitted by rhombohedral lattice with unit cell dimensions a = b = 27.9 Å; γ = 82.9°. But the presence of several unindexed peaks indicates the complexity of the CM sample. These structural differences are attributed to variations in native lipid and pigment compositions, specifically the presence of bacterioruberin in CM, as confirmed by UV-visible spectroscopy. Bacterioruberin, a hallmark of CM, contributes to its red-shifted absorption spectrum, indicative of its organized state within the membrane. However, denaturing 12% polyacrylamide gel electrophoresis (SDS-PAGE) and electron microscopy reveal potential contamination in CM samples, suggesting the need for improved purification protocols. The findings highlight significant structural disparities between PM and CM, with implications for understanding membrane organization. This research underscores the critical role of lipids and pigments in shaping the supramolecular architecture of archaeal membranes and provides a foundation for future studies into their functional adaptations.

The class of G protein-coupled receptors (GPCRs) represents a ubiquitous family of membrane proteins that selectively interact with a variety of signaling molecules to modulate cellular biochemical and physiological processes. Consequently, the structural and functional investigation of GPCRs is of paramount importance for both fundamental and applied scientific research. However, challenges arise in their recombinant expression, as well as subsequent extraction and purification, due to their inherent thermal instability and low yield. This necessitates the optimization of expression conditions and protocols for solubilization and purification. In this study, we focused on optimizing the expression, solubilization, and purification processes for the angiotensin II type 1 receptor (AT1), which plays a critical role in the physiology of the cardiovascular system. Several critical factors affecting receptor expression levels, yield, and monomericity were identified, facilitating an enhancement in the quality of the produced protein.

Cancer progression is often accompanied with the acquisition of functional anergy by natural killer (NK) cells and their aging. As a result, persistent herpesviruses, such as hCMV and EBV, reactivate. The catalytic subunit of telomerase encoded by hTERT gene may enhance functional and proliferative activity. We aimed to elucidate if NK cells modified for sustained hTERT expression acquire these beneficial characteristics. We examined the proliferative and functional activities of hTERT-NK cells and combined observations with RNA-seq results. Thus, hTERT-NK cells were characterized with an increase in the expression levels of cell cycle genes and better proliferative activity in the third month after isolation. Increased degranulation upon K562 target cell recognition simultaneously with a higher expression level of granzyme B was observed for hTERT-NK cells. An increased level of IFNγ was also noted in hTERT-NK cells. These results reveal that hTERT-NK cells obtain additional advantages due to the stable hTERT expression. hTERT-NK cells are likely to perform high levels of functional activity over long time periods that are commonly needed during cancer treatment to perform immune surveillance and minimize relapse rates.

The work considers the transverse bending of the surface of a bilayer lipid membrane and the lateral pressure profile in the neutral part of the membrane within the framework of the model of lipid molecules as flexible elastic chains. When the shape of the membrane changes, the lateral pressure profile may also change. Using the renorm group, the addition to the lateral pressure profile during transverse bending of the membrane was calculated. The tilt moduli for several lipid species were calculated. Torsional modulus and Gaussian modulus calculations were performed for model membranes consisting of polymer rods. The results of the calculations are compared with available experimental and molecular dynamics data.

This study demonstrates the effect of the rhodocyanine derivative MKT-077 on the function of isolated mitochondria from mouse skeletal muscle. MKT-077 was shown to dose-dependently inhibit mitochondrial respiration fueled by glutamate/malate (complex I substrates) or succinate (complex II substrate). This effect of MKT-077 was accompanied by a decrease in the membrane potential of organelles and was associated with both inhibition of the activity of complexes I and II of the mitochondrial respiratory chain and an increase in the proton permeability of the inner mitochondrial membrane. Molecular docking revealed sites in mitochondrial respiratory chain complex I that have an affinity for MKT-077 comparable to that of the specific inhibitor rotenone. At a concentration of 5 μM, MKT-077 caused a significant increase in hydrogen peroxide production by skeletal muscle mitochondria. However, 1 μM MKT-077 reduced the pro-oxidant effect of antimycin A. In addition, MKT-077 dose-dependently reduced the ability of mitochondria to uptake and retain calcium ions in the matrix. The article discusses the mechanisms of possible action of MKT-077 on the functioning of skeletal muscle mitochondria and their contribution to the side effects observed during the therapy of pathological conditions in vivo using this rhodocyanine derivative.

The work is devoted to the mathematical modeling of the regulation of electron and proton transport in the thylakoid membranes of chloroplasts under different operating conditions of the electron transport chain (ETC). The study is based on the kinetic model that we proposed earlier, which describes the redox transformations of the photosystem 1 (PSI) reaction center and molecules of ferredoxin, plastoocyanin, as well as several forms of plastoquinone molecules (the PSII-related concentrations of PQ_A, PQ_B, and the plastoquinone pool PQ/PQH₂). The induction curve of chlorophyll a fluorescence in the leaves of higher plants adapted to darkness is also modelled. The multiphase kinetic curves, obtained by varying the model parameters reflecting the rate of functioning of the Calvin–Benson cycle and the cyclic electron transport path around PSI, are in satisfactory agreement with the experimental data presented in the literature. The main result of our work is that it mathematically describes how pH-dependent regulatory processes occurring at various sites of ETC of chloroplasts (non-cyclic, cyclic, and pseudocyclic electron transport) are reflected in the kinetics of induction processes (slow induction of chlorophyll a fluorescence and redox transformations of the photoreaction center of PSI in chloroplasts of plants adapted to darkness.

Carbon monoxide (CO) is an endogenous molecule that plays a regulatory role in a number of physiological and pathological processes. It is known that exposure to CO causes headaches. CO is involved in the processes of nociception, neurotransmission and cerebral haemodynamics, and there is also evidence of its anti-nociceptive role. However, the mechanisms through which CO exerts its effects on the meninges and the interaction between CO and ATP, a major inducer of nociceptive activity in trigeminal nerve afferents, remain to be elucidated. The objective of this study was to examine the effect of an exogenous CO on ATP-evoked activity in peripheral afferents using electrophysiological recording of action potentials from the trigeminal nerve in rat half-cranial preparations. The application of a CO donor, specifically CORM-2, like a solution saturated with CO gas, resulted in the activation of afferents and this effect was prevented by the inhibitor of soluble guanylate cyclase (GC)–ODQ. Preliminary CO application suppressed ATP-evoked excitation of trigeminal nerve afferents, and this effect was not mediated by the activation of soluble guanylate cyclase and cyclic nucleotides 8-Br-cGMP and 8-Br-cAMP. We suggest that CO increases the activity of trigeminal afferents through sGC activation and prevents the pro-nociceptive activity of ATP independent of the intracellular levels of cyclic nucleotides.