Institute of
bioorganic chemistry

Scientists from the Laboratory of Neuroreceptors and Neuroregulators of the Institute of Bioorganic Chemistry, Russian Academy of Sciences, in collaboration with colleagues from the Institute of Experimental Chemical Physics named after. V.L. Talroze Federal Research Center for Chemical Physics of the Russian Academy of Sciences, using a combined approach of transcriptomics and proteomics, conducted a comprehensive analysis of the polypeptide composition of the venom of the Central Asian spider Tibellus oblongus. Based on analysis of the EST (Expressed Sequence Tags) database, the amino acid sequences of 345 precursor proteins and 217 mature toxins were determined. Using bottom-up proteomics, 212 natural toxins were detected in the venom sample and the post-translational modifications were confirmed. This is the first time that the primary structure has been determined simultaneously for numerous toxins from one spider species. Analysis of the primary structure indicated that some molecules have an ICK (inhibitor cystine knot) organization common for spider toxins, but a significant part of the toxins represents new structural motifs and have no homology with known peptides. The study was published in the Scientific Data.

Photodynamic therapy (PDT) as a cancer treatment modality is currently attracting increasing attention. However, PDT is also characterized by undesirable effects of sunlight on healthy tissues. Employees of the IBCH RAS have obtained a hybrid protein-peptide construct for selective binding and subsequent photodynamic ablation of cancer cells. A peptide fragment was used as a targeting module, which pH-dependently binds to the cancer cell. A mutant of miniSOG protein covalently linked to the peptide was used as a photosensitising component. It was shown that such a protein-peptide construct selectively binds to HeLa cells at pH below 6.8 and destroys them upon exposure to light. The results demonstrate the possibility of using such complexes for targeted delivery to cancer cells and subsequent high-precision PDT. The work is published in the journal J. Photochem. Photobiol. B: Biol.

Chimeric antigen receptor T cell (CAR-T cells) therapy has gained much attention in recent years owing to its well-recognized success in treating adults and children with B-cell malignancies. Very often CAR therapy can deliver considerable remission rates, and it has the potential to become part of standard-of-care treatment for acute lymphoblastic leukemia (ALL). However, current CAR-T cell therapy is still hampered by a variety of drawbacks. On-target off- tumour toxicity limits the anticancer applicability of chimaeric antigen receptor (CAR) T cells for solid tumours. One of the most troubling issues concerns the frequent induction of Cytokine Release Syndrome (CRS) resulted from overactivation of the T cells and on-target off-tumour effects. CAR therapy involves the injection of living cells with the capacity for replication. Unlike the usual side effects with pharmaceuticals that can be ameliorated by withholding drugs, or reducing dosage, CAR-T is much more difficult to regulate once it is initiated. Incorporating a safety switch for the CAR-T cells will lead to the development of safer immunotherapies. Here we show that the tumour-targeting specificity and activity of T cells with a CAR consisting of an antibody with a lysine residue that catalytically forms a reversible covalent bond with a 1,3-diketone hapten can be regulated by the concentration of a small-molecule adapter that selectively binds to the hapten and to a chosen tumour antigen via a small-molecule binder identified via a DNA-encoded library. The adapter therefore controls the formation of a covalent bond between the catalytic antibody and the hapten and the tethering of the CAR T cells to the tumour cells, and hence the cytotoxicity and specificity of the cytotoxic T cells, as we show in vitro and in mice with prostate cancer xenografts. Such small-molecule switches of T-cell cytotoxicity and specificity via an antigen-independent ‘universal’ CAR may enhance the control and safety profile of CAR-based cellular immunotherapies.

Adhesion of leukocytes is a key stage in their trafficking into sites of inflammation. This process is mediated through the interaction of integrins, selectins or CD44, while the role of galectins is not completely clear. It is known that galectins are capable of interacting with oligolactosamines of endothelial cells, and also that in vitro tandem-type galectins (Gal-4, -8 and -9) bind with high affinity to glycans of the ABH blood group system. This work shows that in a cell lines system gal-9 mediates lymphocyte adhesion to endothelial cells through binding to their H-glycan, suggesting that lymphocyte adhesion to endothelium in the circulation occurs similarly and is regulated by the level of galectin-9 expression. The work was published in the journal Biomolecules. Learn more

Proteins and other biopolymers can form in solution macrocomplexes, which at certain conditions are visible under the microscope («coacervate droplets»). The latter process is known to shape subcellular organization and for a century is considered to also impact plausible life-origin scenarios. Researchers from IBCh RAS and University of Vienna present a newly derived fractal model to describe atomistic structure of such protein condensates and using the N-terminal disordered fragment (80 residues) of the yeast transcription regulator Lge1 as a test system. The proposed theoretical model describes protein condensates across various scales in line with the general principles of colloidal system self-organization. The study combining complementary results of microsecond molecular dynamics simulations and in vitro biophysical experiments has been published in eLife. Learn more