EXPRESSION OF SPP1 AND SPARC GENES IN TUMOR TISSUE OF PATIENTS WITH BREAST CANCER.

BACKGROUND: Breast cancer (BCa) is one of the most common oncological diseases in women in Ukraine and worldwide, which determines the need to search for new diagnostic and prognostic markers. In this aspect, the study of multicellular proteins, in particular osteopontin (OPN) and osteonectin (ON), in BCа tissue is relevant. The aim of the work was to investigate the expression of SPP1 and SPARC at the mRNA and protein levels in BCa tissue and to assess their relationship with the main clinicopathological BCa characteristics and the survival rates of patients. MATERIALS AND METHODS: The work was based on the analysis of the results of the examination and treatment of 60 patients with stage II-III BCa and 15 patients with breast fibroadenomas. SPP1 and SPARC mRNA levels were determined by real-time PCR. The study of the expression of protein products of the SPP1 and SPARC genes was carried out by the immunohistochemical method. RESULTS: We have established that the BCa tissue was characterized by 3.5 (p < 0.05) and 7.4 (p < 0.05) lower levels of SPP1 and SPARC mRNA, respectively, compared to the tissue of benign neoplasms, while OPN and ON expression levels were 1.6 (p < 0.05) and 5.6 (p < 0.05) times higher, respectively, compared to fibroadenoma tissue. The analysis of the relationship between the expression of SPP1 and SPARC at the protein and mRNA levels in BCa tissue and the main clinicopathological BCa characteristics revealed its dependence on the presence of metastases in regional lymph nodes, differentiation grade, and the molecular BCa subtype. Also, high expression levels of SPP1 and OPN were associated with worse patient survival rates. CONCLUSION: The obtained results indicate the perspective of using SPP1 and SPARC expression indices in BCa tissue to assess the aggressiveness of the cancer course and optimize the tactics of treating patients.

Charge carrier transport in PbS films doped with iodine.

The results of the measurements of electrical and Hall resistivities on polycrystalline PbS films doped with iodine obtained through hydrochemical deposition are presented. The analysis of the temperature dependence of resistivity points out the crossover from the hopping mechanism due to thermal delocalization in the impurity band to the variable range hopping mechanism. The increase in the iodine content in the films leads to an increase in the impurity ionization energy. It has been established that the temperature dependence of resistivity over a wide temperature range obeys the inverse Arrhenius law, which is characteristic of disordered polycrystalline films with different sizes and orientations of crystallites relative to the substrate, as confirmed by AFM topography, Raman spectra and X-ray diffraction measurements. We found that the type of charge carrier changes from electrons to holes with an increase in the iodine content. Additionally, for a wide range of iodine doping, the concentration of charge carriers is low, indicating the possible occurrence of a self-compensation mechanism due to the formation of impurity defects.

TUMOR MICROENVIRONMENT-ASSOCIATED miR-7-5p, miR-19a-3p, AND miR-23b-3p EXPRESSION IN PROSTATE CANCER WITH DIFFERENT PROGRESSION RISK.

BACKGROUND: The tumor microenvironment (TME) plays an important role in the occurrence and progression of prostate cancer (PCa). At the same time, the mechanisms and features of the interaction between tumor cells and individual components of the TME in PCa remain not fully elucidated. The aim was to study the expression levels of tumor-associated miR-7-5p, miR-19a-3p, and miR-23b-3p in the PCa tissue and to analyze their relationship with the features of TME. MATERIALS AND METHODS: The work is based on the analysis of the results of the examination and treatment of 50 patients with PCa of stages II-IV. The expression of miRNA in the PCa tissue was analyzed by the real-time polymerase chain reaction. The expression of alpha-smooth muscle actin (α-SMA), vimentin (VIM), and CD68 in PCa tissue was determined by the immunohistochemical method. The identification of mast cells in the PCa tissue was assessed by the histochemical method. RESULTS: The analysis of the expression levels of tumor-associated miRNAs demonstrated that the tumor tissue of patients with a high risk of PCa progression was characterized by 4.93 (p < 0.01) and 8.97 (p < 0.05) times higher levels of miR-19a-3p and miR-23b-3p, respectively, compared to similar indicators in the group of patients with a low risk of PCa progression. The levels of miR-7-5p and miR-19a-3p expression in the PCa tissue correlated with the expression level of α-SMA (r = 0.49 and r = 0.45, respectively; p < 0.05) and VIM (r = 0.45 and r = 0.46; respectively, p < 0.05). A direct relationship (r = 0.44; p < 0.05) was established between the level of miR-7-5p expression and the degree of infiltration of the prostate gland tissue by tumor-associated macrophages. CONCLUSIONS: The features of the expression of tumor-associated miR-7-5p, miR-19a-3p, and miR-23b-3p indicated the prospect of their use as markers of the aggressiveness of the PCa course.

Fibrinogen Bonn (p. Arg510Cys) in the Aα-Chain Is Associated with High Risk of Venous Thrombosis.

INTRODUCTION: Inherited dysfibrinogenemia is a qualitative defect of fibrinogen caused by various mutations among three fibrinogen genes. Dysfibrinogenemia can be associated with an increased risk of thrombosis, bleeding, or both. Here, we report a 36-year-old female with dysfibrinogenemia who experienced two successful pregnancies under thromboprophylaxis after cerebral venous sinus thrombosis (CVST). PATIENTS AND METHODS: In addition to plasmatic coagulation tests, fibrinogen genes FGA, FGB, and FGG were screened using direct genomic DNA sequencing. The structural-functional implications of the detected mutation were analyzed in silico. RESULTS: Inherited dysfibrinogenemia was diagnosed in an index patient after CVST in a risk situation. Anticoagulation with warfarin was stopped after 12 months when the first pregnancy was planned. Pregnancy and spontaneous delivery (2020) was uncomplicated. A second pregnancy was interrupted because of acute cytomegalovirus infection and the third pregnancy was successful in 2022. Pregnancies were accompanied by thromboprophylaxis with enoxaparin 40 mg once daily until 6 weeks postpartum. Substitution of fibrinogen has not become necessary in the index patient so far. Genetic analysis revealed a novel missense mutation (p. Arg510Cys) in the FGA gene ("fibrinogen Bonn") in the index patient, as well as an asymptomatic sister, and their father who experienced recurrent pulmonary embolism. Surface exposure of wild-type Arg510 suggested the mutated Cys510 to form nonnative disulfide bonds with surface-exposed reactive cysteines from other plasma proteins like albumin leading to formation of aggregates and impaired fibrinolysis. CONCLUSIONS: Fibrinogen Bonn might be associated with an increased risk of thrombosis, possibly due to impaired polymerization.

Patient ratings in exercise therapy for the management of tendinopathy: a systematic review with meta-analysis.

OBJECTIVE: To synthesise exercise therapy intervention data investigating patient rating outcomes for the management of tendinopathy. DESIGN: A systematic review and meta-analysis of randomized controlled trials investigating exercise therapy interventions and reporting patient rating outcomes. SETTING: Any setting in any country listed as very high on the human development index. PARTICIPANTS: People with a diagnosis of any tendinopathy of any severity or duration. INTERVENTIONS: Exercise therapy for the management of tendinopathy comprising five different therapy classes: 1) resistance; 2) plyometric; 3) vibration; 4) flexibility, and 5) movement pattern retraining modalities, were considered for inclusion. MAIN OUTCOME MEASURES: Outcomes measuring patient rating of condition, including patient satisfaction and Global Rating of Change (GROC). RESULTS: From a total of 124 exercise therapy studies, 34 (Achilles: 41%, rotator cuff: 32%, patellar: 15%, elbow: 9% and gluteal: 3%) provided sufficient information to be meta-analysed. The data were obtained across 48 treatment arms and 1246 participants. The pooled estimate for proportion of satisfaction was 0.63 [95%CrI: 0.53-0.73], and the pooled estimate for percentage of maximum GROC was 53 [95%CrI: 38-69%]. The proportion of patients reporting positive satisfaction and perception of change increased with longer follow-up periods from treatment onset. CONCLUSION: Patient satisfaction and GROC appear similar and are ranked moderately high demonstrating that patients generally perceive exercise therapies positively. Further research including greater consistency in measurement tools is required to explore and where possible, identify patient- and exercise-related moderating factors that can be used to improve person-centred care. SYSTEMATIC REVIEW REGISTRATION NUMBER: PROSPERO ID=CRD42020168187 CONTRIBUTION OF PAPER.

[Measurement of benzodiazepine receptor agonists metabolites and their concentration in urine]. / Opredelenie metabolitov agonistov benzodiazepinovykh retseptorov i ustanovlenie ikh protsentnogo soderzhaniya v moche.

The study objective was to detect and measure the ratio of metabolites of benzodiazepine receptor agonists in urine during forensic chemical and chemical and toxicological studies, as well as to characterize the main metabolites to use them to confirm the oral intake of the test substances. Data on the presence of metabolites in the urine will allow us to reliably confirm the intake of zaleplon, zopiclone, clobazam, and phenazepam and determine the routes of administration (intake) into the body of the victim. Benzodiazepine derivatives (clobazam and phenazepam) and non-benzodiazepines (zaleplon and zopiclone) have different chemical structures and similar mechanisms of action resulting in a similar clinical presentation of side effects and the need for forensic chemical study according to poisoning symptoms. Metabolites of benzodiazepine receptor agonists and their ratio in urine after oral administration were measured: zaleplon (parent compound), deethylzaleplon, 5-oxozaleplon, 5-oxodeethylzaleplon, oxozaleplon glucuronide; zopiclone (parent compound), zopiclone-N-oxide, N-desmethylzopiclone; clobazam (parent compound), N-desmethylclobazam, 4-hydroxyclobazam, hydroxydesmethylclobazam; phenazepam (parent compound) and 3-hydroxyphenazepam. It is advisable to determine zaleplon in urine by the presence of 5-oxaleplon (97% of the total amount of metabolites), zopiclone by zopiclone-N-oxide (86% in urine), clobazam by the parent compound (61% in urine), phenazepam by the parent compound (90-100% in urine).

Experiences in Routine Genetic Analysis of Hereditary Hemorrhagic, Thrombotic, and Platelet Disorders.

Hemostasis is a complex and tightly regulated system that attempts to maintain a homeostatic balance to permit normal blood flow, without bleeding or thrombosis. Hemostasis reflects the subtle balance between procoagulant and anticoagulant factors in the pathways of primary hemostasis, secondary hemostasis, and fibrinolysis. The major components in this interplay include the vascular endothelium, platelets, coagulation factors, and fibrinolytic factors. After vessel wall injury, the subendothelium is exposed to the blood stream, followed by rapid activation of platelets via collagen binding and von Willebrand factor-mediated platelet adhesion to the damaged vessel wall through platelet glycoprotein receptor Ib/IX/V. Activated platelets change their shape, release bioactive molecules from their granules, and expose negatively charged phospholipids on their surface. For a proper function of this process, an adequate number of functional platelets are required. Subsequently, a rapid generation of sufficient amounts of thrombin begins; followed by activation of the coagulation system and its coagulation factors (secondary hemostasis), generating fibrin that consolidates the platelet plug. To maintain equilibrium between coagulation and anticoagulation, the naturally occurring anticoagulants such as protein C, protein S, and antithrombin keep this process in balance. Deficiencies (inherited or acquired) at any level of this fine-tuned system result in pathologic bleedings or increased hypercoagulability states leading to thrombosis. This review will focus on genetic diagnosis of inherited bleeding, thrombotic, and platelet disorders, discussing strengths and limitations of existing diagnostic settings and genetic tools and highlight some important considerations necessary for clinical application.

Federal medical biological agency of Russia's efforts to support Russian athletes during COVID-19 outbreak.

This paper dwells upon COVID-19-related efforts of the Center for Sports Medicine, Federal Medical and Biological Agency of Russia. The Agency has the following precautions in place: regular polymerase chain reaction (PCR) testing of athletes and staff; double PCR testing before going to training camps or medical examinations; isolating athletes and their traceable contacts when COVID is suspected; observation and isolation wards set up at training camp venues. Athlete vaccination has begun. Athletes are provided online advice on health, diet, and exercising plus special care for chronically ill athletes and remote psychological counseling. Athletes recovering from COVID-19 are offered rehabilitation programs and doctor-supervised return to training. Specialists of the Research Department at FMBA's Center for Sports Medicine carried out a research dedicated to the prevalence of COVID-19 and different variants of its course in Russian athletes. The study period lasted from March to December 2020. A total of 27,438 records were analyzed. In May, June, July and August 2020, the percentage of positive PCR tests for athletes was significantly lower than the nationwide percentage at p < 0.05, Pearson's chi-squared test. However, the differences were nullified by September-October. The disease was mild or asymptomatic in most patients. Athletes of summer sports were found to be most likely to contract COVID-19.

[DEVELOPMENT OF THE HEALTHCARE SYSTEM BASED ON THE CLUSTER APPROACH].

The study substantiates the possibility of the cluster approach for the development of the healthcare system in Russia. The analysis of foreign experience in the functioning of medical clusters made it possible to identify factors that contribute to their successful development. Based on the assessment of the domestic practice of creating clusters in the healthcare sector, their typification was carried out with the identification of groups of high-tech clusters of biomedical technologies and innovations, medical clusters of drug provision and specialized equipment, clusters of medical services, internships and transfer of medical innovations. The grouping of clusters in the healthcare sector operating in the Russian Federation according to the proposed types showed that there are practically no clusters of medical services that are able to bring the quality of medical care to the population to a higher level in the country. The article identifies the problems that prevent the formation of clusters of medical services on the territory of the regions. To solve these problems, an approach was proposed to create a medical technology park on the basis of public-private partnership, which will serve as the basis for a cluster of medical services and built its structural and functional model.

[A case report of familial dyskeratosis congenital. Case report].

Dyskeratosis congenita (DC) is a hereditary syndrome of bone marrow failure, which develops because of telomeres defects and combines with cancer predisposition. Its classical clinical features are skin pigmentation, nail dystrophy, oral leukoplakia (skin-mucosa triad). The goal is to describe the algorithm of diagnosis, clinical specificities of DC and specific treatment for cases of DC in one family. The present report includes descriptions of diagnosis and treatment of family members diagnosed for the first time as having a DC. The report shows an importance of all diagnostic stages: from a medical history and clinical picture to an application of modern high-tech diagnostic methods (flow-FISH, NGS). The report underlines an importance of diagnosis of all family members for excluding an asymptomatic form after a case of DC has been already detected in that family. A high frequency of a toxicity and secondary neoplasia makes it necessary to realize an individual approach at treatment of each patient with DC (the earliest start of androgen treatment, prompt decision of implementation of allogenic hematopoietic stem cell transplantation). The knowledge of pathogenesis, clinical features and principles of diagnosis and therapy of this disease is relevant to pediatricians and hematologists.

[Acute retinal necrosis caused by varicella zoster virus]. / Ostryi nekroz setchatki, vyzvannyi virusom opoyasyvayushchego gerpesa.

Incidence of Herpes Zoster is relatively high. Herpes zoster ophthalmicus is one of the most common forms of the disease. Necrotising herpetic retinopathies (including acute retinal necrosis) are rare and usually these complications are presented in literature as individual cases. However, necrotising herpetic retinopathy can lead to complete loss of visual. The article reviews modern data on causation, diagnosis and treatment of acute retinal necrosis analyzing 40 open access articles from EBSCO published in 2011-2019, and describes the modern views on the prevalence and most important clinical features of herpetic acute retinal necrosis. Some contradictory opinions have been revealed concerning the diagnostic criteria and surgical treatment of acute retinal necrosis.

Supercomputer-Based Ensemble Docking Drug Discovery Pipeline with Application to Covid-19.

We present a supercomputer-driven pipeline for in silico drug discovery using enhanced sampling molecular dynamics (MD) and ensemble docking. Ensemble docking makes use of MD results by docking compound databases into representative protein binding-site conformations, thus taking into account the dynamic properties of the binding sites. We also describe preliminary results obtained for 24 systems involving eight proteins of the proteome of SARS-CoV-2. The MD involves temperature replica exchange enhanced sampling, making use of massively parallel supercomputing to quickly sample the configurational space of protein drug targets. Using the Summit supercomputer at the Oak Ridge National Laboratory, more than 1 ms of enhanced sampling MD can be generated per day. We have ensemble docked repurposing databases to 10 configurations of each of the 24 SARS-CoV-2 systems using AutoDock Vina. Comparison to experiment demonstrates remarkably high hit rates for the top scoring tranches of compounds identified by our ensemble approach. We also demonstrate that, using Autodock-GPU on Summit, it is possible to perform exhaustive docking of one billion compounds in under 24 h. Finally, we discuss preliminary results and planned improvements to the pipeline, including the use of quantum mechanical (QM), machine learning, and artificial intelligence (AI) methods to cluster MD trajectories and rescore docking poses.

Supercomputer-Based Ensemble Docking Drug Discovery Pipeline with Application to Covid-19.

We present a supercomputer-driven pipeline for in-silico drug discovery using enhanced sampling molecular dynamics (MD) and ensemble docking. We also describe preliminary results obtained for 23 systems involving eight protein targets of the proteome of SARS CoV-2. THe MD performed is temperature replica-exchange enhanced sampling, making use of the massively parallel supercomputing on the SUMMIT supercomputer at Oak Ridge National Laboratory, with which more than 1ms of enhanced sampling MD can be generated per day. We have ensemble docked repurposing databases to ten configurations of each of the 23 SARS CoV-2 systems using AutoDock Vina. We also demonstrate that using Autodock-GPU on SUMMIT, it is possible to perform exhaustive docking of one billion compounds in under 24 hours. Finally, we discuss preliminary results and planned improvements to the pipeline, including the use of quantum mechanical (QM), machine learning, and AI methods to cluster MD trajectories and rescore docking poses.

Whole genome sequence data of Lactobacillus fermentum HFD1, the producer of antibacterial peptides.

Here we report the whole genome sequence of Lactobacillus fermentum HFD1 strain, the producer of antibacterial peptides. The genome consists of one circular chromosome with 2101878 bp in length and GC-content of 51.8%, and includes linear DNA with 5386 bp in length with 100% identity to bacteriophage phiX174. The analysis of the genome has revealed 2049 genes encoding for proteins including 867 proteins without known function and 70 genes encoding for RNAs (10 rRNAs, 59 tRNAs and 1 tmRNA). Putative genes responsible for the biosynthesis of 4 antimicrobial peptides were identified. The NCBI Bioproject has been deposited at NCBI under the accession number PRJNA615901 (https://www.ncbi.nlm.nih.gov/bioproject/PRJNA615901/) and consist of full annotated genome and raw sequence data.

In silico and in vitro evaluation of the impact of mutations in non-severe haemophilia A patients on assay discrepancies.

Haemophilia A (HA) is caused by a lack or reduced amount of factor VIII protein (FVIII). About one-third of patients with non-severe HA carrying specific missense mutations show discrepant results between FVIII activity (FVIII:C), measured by one-stage or chromogenic two-stage assays. The aim of this study was to elucidate the mechanism underlying the assay discrepancy in vitro and in silico. Thirteen missense mutations in the Factor 8-gene associated with discrepant results in patients were transiently expressed. FVIII:C of the mutations was determined using two one-stage assays (FVIII:C1st, FVIII:CBonn) and a two-stage chromogenic assay (FVIII:Cchr). Furthermore, thrombin generation test (TGT) and in silico analysis were performed to investigate the haemostatic potential as well as the structural impact of the variants, respectively. For the majority (9/13) of the analysed mutations, the discrepancy was confirmed. Moreover, we established a modified TGT protocol for in vitro characterization of FVIII. Hence, TGT parameters were significantly impaired in the group of variants associated with higher chromogenic values. Additionally, in silico analysis revealed the impact of the mutations on FVIII protein structure leading to assay discrepancy. Moreover, the data shows that also among one-stage clotting assays, assay discrepancy is observed. Our results show that for the majority of mutations, application of a global assay like TGT method could help to improve diagnosis or correct assessment of the severity of HA.

Selenium Nanocomposites Having Polysaccharid Matrices Stimulate Growth of Potato Plants in Vitro Infected with Ring Rot Pathogen.

The influence of nanocomposites (NC) of selenium in matrices of arabinogalactan (Se/AG) and starch (Se/St) on in vitro vegetation of potato plants, peroxidase activity, and reactive oxygen species has been thoroughly studied. It has been shown that these nanocomposites of selenium have antimicrobial effect to the phytopathogenic bacterium Clavibacter michiganensis ssp. sepedonicus (Cms). In the present investigation, it has been shown that Se/AG NC (6.4% of Se) and Se/St NC (12.0% of Se) have no negative impact on the potato plants healthy and Cms infected, while stimulating their growth, number of leaves and weight of the vegetative part. Se/AG NC has shown a positive effect on potato plants by increasing its immune status by increasing the ROS content and increasing the peroxidase activity. With the use of the element analysis technique, it has been shown that scrutinized nanocomposites are not accumulated in potato plants after the bactericidal processing with the nanocomposites. Se/AG NC and Se/St NC as potential agents used for treatment of potato plants against pathogenic bacteria.

[The role of the immunohistochemical investigations in the documentation of intravitality and severity of the gunshot injuries to the soft tissues]. / Rol' immunogistokhimicheskogo issledovaniia v ustanovlenii prizhiznennosti i vyrazhennosti ognestrel'nykh povrezhdenii miagkikh tkanei.

The objective of the present study was to determine intravitality and severity of a gunshot-inflicted trauma making use of the immunohistochemical (IGH) methods for the evaluation of the injury to the soft tissues of the wound canal. The immunohistochemical methods were employed to estimate the expression of fibrinogen and vimentin. The positive immunohistochemical reaction was obtained in the fibrinogen assay whereas the reaction in the zone of necrosis was negative. These findings give evidence of the thermal impact produced by the firearm projectile on the soft tissues. Deformation of the cytoskeleton registered in the IGH test for vimentin suggests its disintegration and therefore the severity of the injury. It is concluded that the investigations with the use of the immunohistochemical methods, make it possible to identify the affected parts of the wound canal.

[The pilot studies for the development of the combined methods of rehabilitation of the patients as exemplified by the application of phyto- and physiotherapeutic modalities]. / Poiskovye issledovaniia pri razrabotke kompleksnykh metodov reabilitatsii bol'nykh na primere fito- i fizioterapii.

Under the modern market conditions, the process of development of the methods for the combined rehabilitation of the patients is becoming increasingly more complicated. For the reduction of potential risks and leveling the factors responsible for the uncertain market situation influencing the creation of new methods, it is necessary to carry out the full-scale pilot studies with the use of the marketing analysis methods. The objective of the present work was to create and elaborate the rationale for the graphological structure (the scheme) of the process of exploratory research with a view to the development of the combined rehabilitation methods as exemplified by phyto- and physiotherapeutic modalities. The work is based on the application of the existing approaches to the structural, comparative, systemic, and situational analyses. The proposed graphological structure (scheme) of the exploratory research process consists of 6 stages. Its distinctive features are as follows: a fractional stage by stage evaluation of a variety of issues including the study of physical factors, characteristic of the means of herbal medicine with special reference to the mechanisms of their production and application under the current market conditions, monitoring the marketing environment with the constant focus on the trends and behavior of the target market, the parallel pursuing of serial studies with the application of the iterative procedures; the use of the previously created data bank to expand medical services at the stages of development and maturation of the life cycle, the evaluation of the possibility of establishment of the industry of parapharmaceutical products.

[Clinical pathomorphology and tanatogenesis of various forms of alcoholic intoxication]. / Klinicheskaia patomorfologiia i tanatogenez razlichnykh form alkogol'noi intoksikatsii.

The objective of the present study was to identify the clinical and pathomorphological changes in the internal organs for the elucidation of the cause of death associated with various forms of alcoholic intoxication (chronic alcoholic intoxication, poisoning with surrogate alcohols, etc.). The analysis of the clinical conditions resulting from alcohol abuse has demonstrated that the principal pathology underlying the fatal outcome is complemented by a variety of non-lethal somatic disorders aggravating the patients' condition and enhancing its severity. The clinicians are known to give more attention to the accompanying somatic complications than to the cause underlying the main pathology (alcoholism). Such attitude in the absence of the adequate treatment of the alcohol dependency is neither clinically efficient nor economically appropriate. Poisoning with surrogate alcohols is characterized by the pulmonary-cerebral variant of tanatogenesis in the combination with hypercoagulation and the erosive processes in the gastrointestinal tract whereas death from alcoholic intoxication is usually associated with heart tanatogenesis.

Endonuclease Activity of MutL Protein of the Rhodobacter sphaeroides Mismatch Repair System.

We have purified the MutL protein from Rhodobacter sphaeroides mismatch repair system (rsMutL) for the first time. rsMutL demonstrated endonuclease activity in vitro, as predicted by bioinformatics analysis. Based on the alignment of 1483 sequences of bacterial MutL homologs with presumed endonuclease activity, conserved functional motifs and amino acid residues in the rsMutL sequence were identified: five motifs comprising the catalytic site responsible for DNA cleavage were found in the C-terminal domain; seven conserved motifs involved in ATP binding and hydrolysis and specific to the GHKL family of ATPases were found in the N-terminal domain. rsMutL demonstrated the highest activity in the presence of Mn2+. The extent of plasmid DNA hydrolysis declined in the row Mn2+ > Co2+ > Mg2+ > Cd2+; Ni2+ and Ca2+ did not activate rsMutL. Divalent zinc ions inhibited rsMutL endonuclease activity in the presence of Mn2+ excess. ATP also suppressed plasmid DNA hydrolysis by rsMutL. Analysis of amino acid sequences and biochemical properties of five studied bacterial MutL homologs with endonuclease activity revealed that rsMutL resembles the MutL proteins from Neisseria gonorrhoeae and Pseudomonas aeruginosa.