Vol 88, No 10 (2023)

In the bioenergetics studies, the direct electrometric method played an important role. This method is based on measuring the electrical potential difference (Δψ) between two compartments of the experimental cell generated by some membrane proteins. These proteins are incorporated into closed lipid-protein membrane vesicles associated with an artificial lipid membrane that separates the compartments. The very existence of such proteins able to generate Δψ was one of the consequences of Peter Mitchell’ s chemiosmotic concept. The discovery and investigation of their functioning contributed to the recognition of this concept and, eventually the well-deserved awarding of the Nobel Prize to P. Mitchell. Lel A. Drachev (1926-2022) was one of the main authors of the direct electrometrical method. With his participation, key studies were carried out on the electrogenesis of photosynthetic and respiratory membrane proteins, including bacteriorhodopsin, visual rhodopsin, photosynthetic bacterial reaction centers, cytochrome oxidase and others.

This work represents an overview of electron transport regulation in chloroplasts as considered in the context of structure-function organization of photosynthetic apparatus in plants. A basic focus of the article is concentrated on a bifurcated oxidation of plastoquinol by the cytochrome b6f complex, which represents the rate-limiting step of electron transfer between photosystems 2 and 1. Electron transport along the chains of the noncyclic, cyclic and pseudocyclic electron flow, their relationships to generation of the trans-thylakoid difference in electrochemical potentials of protons in chloroplasts, and the pH-dependent mechanisms of regulation of the cytochrome b₆f complex, are considered. Redox reactions with the participation of molecular oxygen and ascorbate, the alternative mediators of electron transport in chloroplasts, have also been discussed.

Electrical signals (ESs) of plants occurring under the action of various external factors play an important role in adaptation to changing environmental conditions. The generation of ESs in higher plant cells is associated with the activation of Ca²⁺, K⁺, and anion fluxes, as well as changes in the activity of plasma membrane H⁺-ATPase. In the present review, the molecular nature of ion channels contributing to ESs transmission in higher plants is analyzed based on the comparison of data from molecular-genetic and electrophysiological studies. Based on such characteristics of ion channels as selectivity, activation mechanism, and intracellular and tissue localization, those ion channels that meet the requirements for potential participants of ESs generation were selected from a wide variety of ion channels in higher plants. Analysis of the data of experimental studies performed on mutants with suppressed or enhanced expression of a certain channel gene revealed those channels whose activation contributes to ESs formation. The channels responsible for Ca²⁺ flux during ESs generation include channels of GLR family, for K⁺ flux - GORK, for anions - MSL. Consideration of the prospects for further studies suggests the need to combine electrophysiological and genetic approaches along with the analysis of ion concentrations in intact plants within a single study.

This treatise gives an overview of current thinking on the mechanism of generation of a transmembrane electric potential difference (Δψ) during the catalytic cycle of a bd-type triheme terminal quinol oxidase. It is assumed that the main contribution to the Δψ formation is made by the movement of H⁺ across the membrane along the intraprotein hydrophilic proton-conducting pathway from the cytoplasm to the active site for oxygen reduction of this bacterial enzyme.

The diversity of retinal-containing proteins in nature is extremely large. The fundamental similarity of the structure and photochemical properties unites them into one family. However, there is still a debate about the origin of retinal-containing proteins: divergent or convergent evolution? In this review, based on the results of our own and literature data, a comparative analysis of the similarities and differences in the photoconversion of rhodopsin types I and II is carried out. The results of experimental studies of direct and reverse photoreactions of rhodopsin types I (bacteriorhodopsin) and II (visual rhodopsin) in the femto- and picosecond time interval, photo-reversible reaction of rhodopsin type II (octopus rhodopsin), photovoltaic reactions of rhodopsin types I and II, as well as quantum chemical calculations of forward photoreactions of bacteriorhodopsin and visual rhodopsin are presented. The question of the probable convergent evolution of rhodopsin types I and II is discussed.

Channelrhodopsins stand out among other retinal proteins because of their capacity to generate passive ionic currents following photoactivation. Owing to that, channelrhodopsins are widely used in neuroscience and cardiology as instruments for optogenetic manipulation of the activity of excitable cells. Photocurrents generated by channelrhodopsins were first discovered in the cells of green algae in the 1970s. In this review we describe this discovery and discuss the current state of research in this field.

The absorption dynamics of chlorophyll a in a symmetric tetrameric complex of the water-soluble chlorophyll-binding protein BoWSCP was measured by the broadband femtosecond laser pump-probe spectroscopy within the range from 400 to 780 nm with a time resolution of 20 f-200 ps. When BoWSCP was excited in the region of the Soret band at a wavelength of 430 nm, a nonradiative intramolecular conversion S₃ → S₁ was observed with a characteristic time of 83 ± 9 fs. When the complex was excited in the region of the Q_y band at a wavelength of 670 nm, a relaxation transition between two excitonic states of the chlorophyll dimer was observed with a time of 105 ± 10 fs. Absorption spectra of excited singlet states S₁ and S₃ of chlorophyll a were obtained. It has been demonstrated that the delocalization of the excited state between exciton-coupled Chl molecules in the BoWSCP tetramer changes in time and depends on the excitation energy. Upon excitation of BoWSCP, an ultrafast photochemical reaction is observed in the Soret region, apparently due to the reduction of tryptophan in the vicinity of chlorophyll.

Bronchial asthma (BA) is a heterogeneous chronic inflammatory disease of the respiratory tract. Allergic asthma is the most common (up to 80% of cases) phenotype developing through Th2-dependent mechanisms involving cytokines: IL-4, IL-5, IL-9 and IL-13. The genes encoding Th2-cytokines have a mosaic structure (encode exons and introns). Therefore, several mature mRNA transcripts and protein isoforms can be derived from a single mRNA precursor through alternative splicing, and they may contribute to BA pathogenesis. Analysis of published studies and databases revealed the existence of alternative mRNA transcripts for IL-4, IL-5, and IL-13. Alternative transcripts of IL-4 and IL-5 carry open reading frames and therefore can encode functional proteins. It was shown that not only alternative mRNA transcripts are exist for IL-4, but alternative protein isoforms, as well. Natural protein isoform IL-4δ2 lacking part encoded by exon-2 was identified. Similarly, alternative mRNA transcript omitting exon-2 (IL-5δ2) was also identified for IL-5. In this review, we summarize current knowledge about identified alternative mRNA transcripts and protein isoforms of Th2-cytokinins, first of all IL-4 and IL-5. We have analyzed biological properties of alternative variants of these cytokines, their possible role in the allergic asthma pathogenesis, and considered their diagnostic and therapeutic potential.

Cytochromes P450 are unique family of isozymes, discovered in all kingdoms of living species (in animals, bacteria, plants, fungi, archaea). The main functional role of the cytochromes P450 is biotransformation of exogenous and endogenous compounds. This review is highlighted problem of enchasing effectivity of electrocatalysis of cytochromes P450, enzymes that have unique capabilities both for biosensors’ design and for biotechnological application. In this review paper, we summarize main methods and modern trends based on biochemical mechanism of cytochromes P450 for development of reconstructing and electrochemical catalytic systems for practical application of these enzymes.

Cataloging human proteins, determining their level of content, cellular localization, function performed, and potential medical significance are important tasks facing the global proteomic community. At present, the localization and functions of protein products for almost half of the protein-coding genes are unknown or poorly understood. The study of the organelle proteome is a promising approach to reveal the localization and functions of human proteins. The nuclear proteome is of particular interest because many nuclear-localized proteins, such as transcription factors, perform regulatory functions that determine cell fate. According to the results of a meta-analysis of the nuclear proteome, or nucleome, of HL-60 cells treated by all-trans-retinoic acid (ATRA), it was revealed that the function and localization of the protein product of the SOWAHD gene is poorly understood, in addition, there is no comprehensive information on the expression of SOWAHD at the protein level. In HL-60 cells for the protein-coding gene SOWAHD, mRNA expression was determined at the level of 6.4 ± 0.7 transcripts per million molecules. Using targeted mass spectrometry, the content of SOWAHD protein was measured in the range of 0.27-1.25 fmol/µg of total protein. Using stable isotope pulse-chase labeling, the half-life for the protein product of the SOWAHD gene was determined to be approximately 19 h. Proteomic profiling of the nuclear fraction of HL-60 cells showed that the SOWAHD protein content increased during ATRA-induced granulocytic differentiation, peaking at 9 h after the addition of the inductor and followed by a decrease at later time points. The results of the study indicate for the first time the nuclear localization and involvement of the protein product of the SOWAHD gene in induced granulocytic differentiation.