Doklady Biochemistry and Biophysics最新文献

Rhamnogalacturonans I (RGs-I) are complex, multifunctional pectic polysaccharides found in plant cell walls and seed mucilages. Their structure varies based on the source, tissue type, and growth stage. This study investigates the structural peculiarities of different functional types of RG-I from flax, focusing on NMR analysis of RGs-I from seed mucilage, primary cell walls of hypocotyls, and tertiary cell walls of fibers. RG-I from flaxseed mucilage features single-residue side chains of Galp and Fucp, with 55% Rhap substitution at the rare O-3 position, no homogalacturonan, and the presence of acetyl groups. Primary cell wall RG-I includes homogalacturonan (up to 50% of the total backbone), 54% Rhap substitution at O-4, and short β-(1 → 4)-galactan and α-(1 → 5)-arabinan side chains (averaging 2–3 residues), with 17% represented by single Ara and Gal units, along with acetyl, feruloyl, and benzoyl groups. The tertiary cell wall RG-I has a pure backbone without homogalacturonan and the highest Rhap substitution at O-4 (72%) by long galactan side chains (up to 92 residues). Modifications of this RG-I in the cell wall suggest the removal of acetyl groups and trimming of galactan chains (47% reduced to a single residue; longer side chains of up to 16 residues remaining). This research provides insights into the structural diversity of RG-I within a single plant, contributing to the understanding of their functional roles in plant growth and development.

Antibodies to the ganglioside GD2 are used therapeutically, although the mechanism of their interaction with tumor cells antigen is poorly understood. To study the effect of membrane environment on GD2 recognition by antibodies, three synthetic glycolipids—analogs of the ganglioside GD2—were obtained. These glycolipids differed in the length of their spacers and the type of lipid moiety. When inserted in the membrane of endothelial cells, they interacted with anti-GD2 antibodies in a paradoxical manner: the spatially most hindered variant (where the oligosaccharide is located in tight proximity to the membrane) interacted better than the others.

The antibiofilm activity of two lectins from the hemolymph of the bivalve mollusk Glycymeris yessoensis (GYL and GYL-R) against opportunistic bacteria, Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, was studied for the first time. Lectins significantly suppressed the formation of biofilms of both S. aureus and E. coli. The most pronounced effect for GYL was demonstrated against S. aureus, and for GYL-R against E. coli, which is determined by the carbohydrate specificity of the antibacterial action of these lectins. In addition, GYL and GYL-R caused partial destruction of already formed biofilms by interacting with the exopolysaccharide matrix that forms the basis of bacterial biofilms.

The serum of people with blood group O contains not only classical anti-A and anti-B, but also anti-A,B antibodies, i.e., those whose Fab region equally recognizes both the A and B blood group antigens. The common epitope of the A and B antigens, recognized by these antibodies, is located strictly on one side of the tetrasaccharide molecule, which was shown by studying their complex with anti-A,B antibodies using the Saturation Transfer Difference (STD NMR) spectroscopy.

In isolated Saccharomyces cerevisiae cell walls (CWs) obtained without using denaturing agents, Bgl2p demonstrates hydrolysis of the laminaripentaose forming a disaccharide and generates the glucanosyltransglycosylase activity product, laminarioctaose, that confirms the results obtained previously for the enzyme isolated using denaturing conditions. Activity is detected in the CWs of the parental yeast strain and is not detected in the CWs of a strain with a deletion of BGL2 gene, that lacks Bgl2p. For the first time, Bgl2p activity was investigated under conditions as similar as possible to in vivo; the absence of the influence of high-molecular-weight polyphosphates, universal regulators of protein functioning, and resistance to the hydrolysis of trypsin together allow us to put forward a hypothesis about the significant protection of the Bgl2p molecule by the CW components.

Amaranthin-like proteins are lectins with distinct domain organization, but their functions in plants remain unclear. Flax (Linum usitatissimum) has one of the largest Amaranthin protein family among plant species, with 19 members grouped into three types of domain combinations: single amaranthin domain (A), two amaranthin domains with one aerolysin domain (AAT), and one or two amaranthin domains with one Bet v 1 domain (AB/AAB). In this study, we examined the expression of 13 amaranthin-like genes. Genes encoding proteins with a single amaranthin domain were active during early development and showed temporary upregulation in phloem fibers and xylem tissues after gravistimulation, suggesting possible roles in cell wall rearrangement and biosynthesis. AB2 and AAB2 genes were mainly expressed in phloem fibers at later stages, indicating possible involvement in phloem fiber formation. AAT1 was the only gene clearly expressed during intrusive phloem fiber growth. These results reveal that the different protein domain combinations correspond to distinct, tissue- and stage-specific gene expression patterns, pointing to specialized roles in phloem fiber formation, xylem development, and cell wall dynamics, and highlight candidate genes for further functional studies.

High genome variability of the 7th cholera pandemic agent, V. cholerae El Tor, led to emergence of genovariants with a distinct set of altered genes. The aim of the work was to analyze the dynamics of changes in pathogenicity, epidemicity, as well as drug resistance and phylogeny in toxigenic strains of V. cholerae El Tor isolated in Russia and endemic regions during three waves of ongoing pandemic. Materials and methods. We used whole-genome nucleotide sequences of 155 strains, obtained by us (42) and taken from the NCBI Genbank (113). DNA sequencing was performed on Ion PGM platform. Phylogenetic relations were determined based on the Bayesian analysis of core SNPs obtained using Snippy 4.6 software package. Antibiotic resistance was assessed using the disk diffusion test. Results. SNP data revealed that the studied strains (1970–2023) can be divided into three clusters. A clear correlation between each-cluster strain genotype and relevant isolation timing was observed. Separation of genetically altered cluster II and III strains isolated during the 2nd and 3rd waves of the pandemic from typical cluster I strains is associated with the acquisition of new DNA regions and mutations in pathogenicity and drug resistance genes. Due to different combination of mutations, cluster III strains are genetically heterogeneous. Genome comparison showed that this diversity increased dramatically during the 3rd wave, which led to emergence of new genovariants with higher pathogenic and epidemic potential. It is demonstrated that antibiotic resistance in strains both from endemic regions and Russia over the past 30 years (1993–2023) has undergone significant changes. The changing drug resistance clearly correlated with the occurrence of mutations in various pathogenicity genes. Conclusions. It is shown that, over the past two decades, the agent genome underwent a rather rapid change resulting in emergence of various genovariants. A change in the pathogen variants in Russia has been established. Strains combining genetic markers of hyper-virulence and multiple drug resistance are of particular concern. Genome variability of the strains identified points at a need for constant genomic surveillance to obtain data on altering epidemically important properties for timely generation of new diagnostic and preventive means.

The application of porous nanomaterials in drug delivery offers a promising strategy to mitigate the adverse side effects of chemotherapy. In this study, we report the synthesis of nanosized NH₂-UiO-66 (Zr) metal-organic frameworks as carriers of doxorubicin. The nanoparticles exhibited high crystallinity with an average size of 44 nm. Surface functionalization with polyethylene glycol (PEG) markedly enhanced their colloidal stability under physiological conditions. Coated NH₂-UiO-66 (Zr)@PEG particles demonstrated prolonged circulation in the bloodstream and a significant reduction of nonspecific accumulation in organs with high vascularization. Importantly, these particles retained their capacity for doxorubicin loading, highlighting their potential for drug delivery.

This work presents the results of the analysis of the effect of the phytohormone salicylic acid on the secretion of proteins to the apoplast of the pea seedlings roots. It is shown that the secretion of a number of defense proteins (β-1,3-glucanase, acid and alkaline endochitinases, disease resistance response protein, and protease inhibitors) is increased, but there is no activation of the expression of the genes encoding these proteins. A distinctive feature of the pea root response to the salicylic acid was the activation of the expression of the genes encoding isoforms of chitinase-like proteins and the secretion of these proteins into the apoplast.

The chromatin of histone genes is associated with specific nuclear biomolecular condensate called the histone locus body (HLB). HLB is the compartment where the transcription of histone genes and processing of their pre-mRNAs coordinated with the cell cycle take place. In this work, the transcriptional histone acetyltransferase coactivator complex SAGA is described as a component of the HLB. Specific subunits of the SAGA complex, Gcn5 and Sgf11 proteins, are present on the chromatin locus of the histone gene cluster and interact with known constant specific structural components of the HLB (Mxc, FLASH, and Mute proteins).