Published on: 2026-05-13
Source: Saint Petersburg Polytechnic University of Peter the Great –
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Scientists from Saint Petersburg Polytechnic University of Peter the Great for the first time in the world demonstrated the process of forming loops from DNA molecules under the influence of the SMC (Structural Maintenance of Chromosomes) complex of the bacterium Ureaplasma parvum. These complexes are essential for the bacterium: they package DNA, participate in its “repair,” and also help the cell fight foreign DNA molecules, including viral ones. Understanding the fundamental basis of the mechanism of SMC complexes’ work may form new approaches for antibacterial therapy in the future. The research was supported by the Russian Science Foundation grant 24-74-10022.The results are published in the international scientific journal Archives of Biochemistry and Biophysics.
In every living cell, whether a bacterium or a human cell, there exists at least one SMC complex. At the molecular level, they act somewhat like ‘weavers’: they constantly ‘knit’ multiple loops from a very long DNA molecule and maintain the cell’s genome in a compact and orderly form. Without this extrusion of loops, the cell could become ‘entangled’ in its own genetic material. Some of the SMC-like complexes participate in DNA repair, while others help the cell fight foreign DNA molecules, such as viral ones. In modern science, there remain many gaps in the understanding of the mechanisms of SMC complex function.For example, for most SMC bacterial complexes, until now it has not been possible to demonstrate the ability to “tie” loops.
Scientists have obtained experimental data showing that the SMC complex performs loop extrusion in the “minimal” bacterium U. parvum. It is structured significantly more simply than “full-fledged” bacteria such as Bacillus subtilis and Escherichia coli. Researchers used many methods, ranging from standard genetic engineering and molecular biology techniques to unique single-molecule methods, which allow one to see under a microscope individual DNA molecules and how SMC complexes “weave” loops from them.
Our study primarily has fundamental significance: the results refine the understanding of the structure of SMC bacterial complexes. There are still many gaps in knowledge in this area, so our results and developments can be used in future studies for the characterization of other SMC complexes.Speaking about the practical significance of the work, it can be assumed that SMC complexes, being vital for living cells, may in the future become one of the new targets for drugs, including antibacterial agents, noted engineer-researcher of the Scientific Research Complex “Nanobiotechnology”, associate professor of the Higher School of Biomedical Systems and Technologies at SPbPU Alexey Vedyaykin.
During the study, the behavior of the U. parvum SMC complex was compared with the behavior of an analogous “full-fledged” bacterial complex of B. subtilis. It turned out that under the same experimental conditions, the B. subtilis SMC complex is not capable of “tying” DNA loops. This difference may indicate either that the latter complex lacks “weaving” skills entirely, or that the given complex is more complex in structure and requires the involvement of other “actors” for full functionality. The authors of the study plan to determine the real reason for this difference.
The work was performed at the NIK “Nanobiotechnologies” using equipment from the Central Collective Use Facility “Analytical Center for Nano- and Biotechnologies” of SPbPU. The research was supported by a grant from the Russian Scientific Foundation.
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