HMGB3 protein belongs to the group of HMGB proteins from the superfamily of nuclear proteins with high electrophoretic mobility. HMGB proteins play an active part in almost all cellular processes associated with DNA—repair, replication, recombination, and transcription—and, additionally, can act as cytokines during infectious processes, inflammatory responses, and injuries. Although the structure and functions of HMGB1 and HMGB2 proteins have been intensively studied for decades, very little attention has been paid to HMGB3 until recently. In this review, we summarize the currently available data on the molecular structure, post-translational modifications, and biological functions of HMGB3, as well as the possible role of the ubiquitin–proteasome system-dependent HMGB3 degradation in tumor development.

This paper presents the results of the study of the effect of water with deuterium content of 750 ppm, used for simulation of the isotopic composition of water in ice caps at the poles of Mars, on oxidative processes in the liver tissue and blood of laboratory animals. It was found that prolonged consumption of deuterium-enriched water contributed to an increase in the deuterium content in blood plasma up to 487 ppm. As a result, increased antioxidant activity in the liver tissues and blood plasma was observed. In addition, the effect of a medium that contains 487 ppm of deuterium on the secondary structure of bovine serum albumin was also investigated in a model experiment. A decrease in intensity of circular dichroism and intrinsic tryptophan fluorescence spectra was found. This indicates that there are conformational changes in the structure of this protein at a time when the content of deuterium increases in the incubation medium. The results of our research point to the need to explore further the effect of drinking diet with the increased deuterium to (from 700 to 1000 ppm) on living systems, to explain the possibility for life on Mars.

Non-histone nuclear proteins HMGB1 and HMGB2 (High Mobility Group) are involved in many biological processes, such as replication, transcription, and repair. The HMGB1 and HMGB2 proteins consist of a short N-terminal region, two DNA-binding domains, A and B, and a C-terminal sequence of glutamic and aspartic acids. In this work, the structural organization of calf thymus HMGB1 and HMGB2 proteins and their complexes with DNA were studied using UV circular dichroism (CD) spectroscopy. Post-translational modifications (PTM) of HMGB1 and HMGB2 proteins were determined with MALDI mass spectrometry. We have shown that despite the similar primary structures of the HMGB1 and HMGB2 proteins, their post-translational modifications (PTMs) demonstrate quite different patterns. The HMGB1 PTMs are located predominantly in the DNA-binding A-domain and linker region connecting the A and B domains. On the contrary, HMGB2 PTMs are found mostly in the B-domain and within the linker region. It was also shown that, despite the high degree of homology between HMGB1 and HMGB2, the secondary structure of these proteins is also slightly different. We believe that the revealed structural properties might determine the difference in the functioning of the HMGB1 and HMGB2 as well as their protein partners.

High-Mobility Group (HMG) chromosomal proteins are the most numerous nuclear non-histone proteins. HMGB domain proteins are the most abundant and well-studied HMG proteins. They are involved in variety of biological processes. HMGB1 and HMGB2 were the first members of HMGB-family to be discovered and are found in all studied eukaryotes. Despite the high degree of homology, HMGB1 and HMGB2 proteins differ from each other both in structure and functions. In contrast to HMGB2, there is a large pool of works devoted to the HMGB1 protein whose structure–function properties have been described in detail in our previous review in 2020. In this review, we attempted to bring together diverse data about the structure and functions of the HMGB2 protein. The review also describes post-translational modifications of the HMGB2 protein and its role in the development of a number of diseases. Particular attention is paid to its interaction with various targets, including DNA and protein partners. The influence of the level of HMGB2 expression on various processes associated with cell differentiation and aging and its ability to mediate the differentiation of embryonic and adult stem cells are also discussed.

Water containing 750 ppm deuterium was used to simulate the isotopic composition of water in ice caps at the poles of Mars and tested for effect on oxidative processes in the liver and blood of laboratory animals. Prolonged consumption of deuterium-rich water was found to increase the deuterium content in the blood plasma to 487 ppm. Higher antioxidant activity was consequently observed the liver and blood plasma. The effect of a medium containing 487 ppm deuterium on the secondary structure of bovine serum albumin (BSA) was additionally studied in a model experiment. Lower intensities were observed in circular dichroism (CD) and intrinsic tryptophan fluorescence spectra, indicating that conformational changes arose in albumin structure when the deuterium content increased in the incubation medium. The study provides a basis for further research of how drinking water with a higher deuterium content (700–1000 ppm) affects living systems, to understand the possibility of life on Mars.

The nonhistone chromosomal protein HMGB1 and histone H1 are chromatin linker proteins. The functions of linker proteins are closely related to their conformational state. The structure of proteins that play a key role in the formation of higher levels of chromatin structural organization is being actively studied. In this study, a comparative analysis of the secondary structure of the linker histone H1 and the nonhistone protein HMGB1 was carried out. Using circular dichroism in the UV region and FTIR spectroscopy, it was shown that positively charged histone H1 binds to the C-terminal fragment of HMGB1, stabilizing the resulting complex and inducing the formation of additional α-helical regions in both proteins.

На примере анализа инфракрасных спектров комплексов ДНК с дихлородиамминплатиной(II) предпринята попытка систематического отнесения полос, наблюдаемых в интервале 1800-800 см-1 при измерении образцов в таблетках KBr. На основе произведенной декомпозиции спектров ДНК и ее комплексов с дихлородиамминплатиной(II) показано, что, полученные результаты хорошо согласуются с прямыми структурными данными, а также ранее проведенными измерениями в растворах. Показано также, что в спектрах ДНК в таблетках KBr одновременно наблюдаются маркеры A- и B-форм ДНК.

Abstract —A systematic assignment of bands observed in the range of 1800–800 –1 cm when measuring samples in KBr pellets based on the example of the analysis of infrared spectra of DNA complexes with dichlorodiammineplatinum(II) was performed. Based on the performed decomposition of the spectra of DNA and its complexes with dichlorodiammineplatinum(II), it was shown that the results are in good agreement with the direct structural data, as well as with previous measurements in solution. It was also shown that markers of the A- and B-forms of DNA are simultaneously observed in the DNA spectra in KBr pellets.

Проведено сравнение радиационного эффекта гамма-излучения и протонов высоких энергий (1000 МэВ) при облучении ДНК дозами 30 и 50 Гр в водно-солевых растворах (5 и 150 мМ NaCl). Использовали спектральные методы (спектроскопия УФ-поглощения, метод Спирина, спектрофотометрическое плавление ДНК, круговой дихроизм), которые позволяют оценить количество разрушенных азотистых оснований и повреждение вторичной структуры ДНК. Обнаружено, что при указанных условиях протонное излучение вызывает более сильные разрушения азотистых оснований и вторичной структуры ДНК, чем такая же доза гамма-излучения. В ДНК, облученной протонами, предположительно образуются сшивки; вероятность их появления увеличивается с ростом ионной силы облучаемого раствора.

HMGB1 is one of the key proteins of the cell. HMGB1 performs its main functions predominantly in the cell nucleus, as an essential component of DNA–protein and multiprotein complexes. It plays an important role in various cellular processes, such as transcription, replication, and DNA repair. However, it has also been found outside the nucleus: in the cytoplasmic and extracellular space. Despite numerous publications on the structure and functioning of HMGB1, the molecular mechanisms that underlie the vast variety of functions performed by this protein still remain unclear. In this paper, we report recent data on the organization of the protein structure and its effects on HMGB1 interactions with DNA and other proteins.

The non-histone chromosomal proteins HMGB1 and HMGB2 were found in the cells of all studied eukaryotes. They are involved in cell decision and many biological processes such as replication, transcription, repair, etc. In this work, the secondary structure of the HMGB1 and HMGB2 proteins was studied by the circular dichroism method. It was shown that, despite the high homology between them, the secondary structure of these proteins is different. The revealed structural features, most likely, should influence their functions in the cell nucleus, in particular, the interaction with DNA and other proteins.

Белок HMGB1 является одним из ключевых клеточных белков. Основные функции HMGB1 выполняет в ядре, являясь компонентом сложных белок-белковых и ДНК-белковых комплексов. Прежде всего HMGB1 играет важную роль в основных клеточных процессах: транскрипции, репликации, репарации. Помимо ядра этот белок обнаружен в цитоплазматическом и внеклеточном пространстве. Несмотря на достаточно большое количество работ, посвященных исследованию структуры и функций белка HMGB1, на сегодня нет четкого представления о молекулярных механизмах, определяющих разнообразие выполняемых им функций. В работе рассматриваются особенности структурной организации белка HMGB1 и ее влияние на взаимодействие белка с ДНК и другими белками.

In this study, we compared the effects of gamma and high-energy proton radiation (1000 MeV) on DNA in aqueous saline solutions (5 and 150 mM NaCl) at doses of 30 and 50 Gy. We used spectral methods (the ultraviolet absorption method, spectrophotometric methods for nucleic acid quantification, spectrophotometric DNA melting, and circular dichroism) for the estimation of the number of damaged nitrogenous bases and damage of the secondary DNA structure. It was found that under these conditions, proton radiation causes more severe destruction of nitrogenous bases and the secondary DNA structure than exposure to gamma rays at the same dose. In DNA irradiated with protons, the formation of crosslinks is possible and the probability for crosslinking increases with the increase of the ionic strength of the irradiated solution.

Abstract—In the first part of this review (Biophysics, 63, 858 (2018)), the structure of H1 family linker histones, their posttranslational modifications, as well as the role of H1 histone in the formation of compact transcriptionally inactive chromatin, were considered. The second part is devoted to the role of H1 family linker histones in the structural organization of chromatin at different levels: from nucleosomes to metaphase chromosomes. The mechanisms of interaction of H1 histone with other elements of chromatin, including with DNA and nuclear proteins, are discussed.

Abstract The structural organization of DNA in complex with linker histone H1 and non-histone chromosomal protein HMGB1 in presence of calcium and manganese ions have been studied using FTIR and UV circular dichroism spectroscopy. We have demonstrated that the presence of calcium ions leads to the formation of highly ordered DNA-H1-HMGB1 structures, while manganese ions decrease the order in the earlier reported nanoscale complexes.

Using UV absorption spectroscopy and circular dichroism, we studied the interaction of DNA-cisplatin complexes with nonhistone chromosomal proteins HMGB1 and HMGB2. It was shown that the presence of platinum ions affected the ability of HMGB2 to form large supramolecular complexes with DNA. The role of C-terminal domain of the HMGB1/2 proteins is discussed.

E. V. Chikhirzhina1, A. D. Garifullin2, A. Yu. Kuvshinov2, L. V. Plotnikova3, A. M. Polyanichko1,3, E. A. Telnaya3, S. V. Voloshin2,4,5 1 Institute of Cytology of the Russian Academy of Sciences, 4, Tikhoretsky pr., St. Petersburg, 194064, Russian Federation 2 Russian Scientific Research Institute of Hematology and Transfusiology, 16, 2-ya Sovetskaya ul., St. Petersburg, 191024, Russian Federation 3 St. Petersburg State University, 7–9, Universitetskaya nab., St. Petersburg, 199034, Russian Federation 4 North-Western State Medical University named after I. I. Mechnikov, 41, Kirochnaya ul., St. Petersburg, 191015, Russian Federation 5 S. M. Kirov Military Medical Academy, 6, ul. Akademika Lebedeva, St. Petersburg, 194044, Russian Federation

The functioning of DNA in the cell nucleus is ensured by a multitude of proteins, whose interactions with DNA as well as with other proteins lead to the formation of a complicated, organized, and quite dynamic system known as chromatin. This review is devoted to the description of properties and structure of the progenitors of the most abundant non-histone protein of the HMGB family-the HmgB1 protein. The proteins of the HMGB family are also known as "architectural factors" of chromatin, which play an important role in gene expression, transcription, DNA replication, and repair. However, as soon as HmgB1 goes outside the nucleus, it acquires completely different functions, post-translational modifications, and change of its redox state. Despite a lot of evidence of the functional activity of HmgB1, there are still many issues to be solved related to the mechanisms of the influence of HmgB1 on the development and treatment of different diseases-from oncological and cardiovascular diseases to pathologies during pregnancy and childbirth. Here, we describe molecular structure of the HmgB1 protein and discuss general mechanisms of its interactions with other proteins and DNA in cell.