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Most species of the genus Bifidobacterium contain the gene cluster PFNA, which is presumably involved in the species-specific communication between bacteria and their hosts. The gene cluster PFNA consists of five genes including fn3 , which codes for a protein containing two fibronectin type III domains. Each fibronectin domain contains sites similar to cytokine-binding sites of human receptors. Based on this finding we assumed that this protein would bind specifically to human cytokines in vitro . We cloned a fragment of the fn3 gene (1503 bp; 501 aa) containing two fibronectin domains, from the strain B. longum subsp. longum GT15. After cloning the fragment into the expression vector pET16b and expressing it in E. coli , the protein product was purified to a homogenous state for further analysis. Using the immunoferment method, we tested the purified fragment’s ability to bind the following human cytokines: IL-1β, IL-6, IL-10, TNFα. We developed a sandwich ELISA system to detect any specific interactions between the purified protein and any of the studied cytokines. We found that the purified protein fragment only binds to TNFα.

Six genes encoding the bifidobacterial Hanks-type (eukaryote-like) serine/threonine protein kinases (STPK) were identified and classified. The genome of each bifidobacterial strain contains four conserved genes and one species-specific gene. Bifidobacterium longum and Bifidobacterium bifidum possess the unique gene found only in these species. The STPK genes of Russian industrial probiotic strain B. longum B379M were cloned and sequenced. The expression of these genes in Escherichia coli and bifidobacteria was observed. Autophosphorylation of the conserved STPK Pkb5 and species-specific STPK Pkb2 was demonstrated. This is the first report on Hanks-type STPK in bifidobacteria.

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Туберкулез -самая смертоносная бактериальная инфекция из известных человеку, при этом ее лечение осложне-но появлением и быстрым распространением штаммов возбудителя, Mycobacterium tuberculosis, с множественной и широкой лекарственной устойчивостью (МЛУ и ШЛУ). В результате главным требованием к разрабатываемым про-тивотуберкулезным препаратам является использование новых классов химических соединений, поражающих новые биомишени. Серин-треониновые протеинкиназы (СТПК) -перспективные мишени, а аминопиридины и аминопири-мидины, ранее не применявшиеся в качестве противотуберкулезных препаратов, имеют предсказанную активность в отношении СТПК. В данной работе в тест-системе Mycobacterium smegmatis aphVIII+, предназначенной для отбора ингибиторов СТПК на клеточном уровне, был проведен скрининг 192 соединений двух указанных классов. Сначала отобрали 53 соединения с субингибирующей концентрацией до 100 нмоль/диск. Из них 22 соединения проявили активность в тест-системе как ингибиторы СТПК, которая была подтверждена in vitro на белке PknA M. tuberculosis (наивысшее значение показателя ингибирования -26,9 ± 6,1 %). Также отобранные соединения тестировали на ток-сичность in vitro на клетках фибробластов эмбриона человека с использованием МТТ-теста. В результате для дальней-ших исследований в качестве новых препаратов для борьбы с МЛУ-туберкулезом были отобраны 3 ингибитора СТПК с относительно высокой активностью и относительно низкой токсичностью. AMINOPYRIDINE-AND AMINOPYRIMIDINE-BASED SERINE/THREONINE PROTEIN KINASE INHIBITORS ARE DRUG CANDIDATES FOR TREATING DRUG-RESISTANT TUBERCULOSISTuberculosis (TB) is the world's deadliest bacterial infection. Its causative agent Mycobacterium tuberculosis evolves into rapidly spreading multidrug-resistant and extensively drug-resistant (MDR and XDR) strains, which complicates the treatment. Therefore, the use of novel target-specific chemical compounds is crucial for the development of effective antituberculosis agents. Serine/threonine protein kinases (STPKs) of M. tuberculosis are currently considered as attractive drug targets. In turn, aminopyridines and aminopyrimidines that have not been used for TB treatment so far exhibit inhibitory activity towards STPKs. In this study we screened 192 aminopyridine-and aminopyrimidine-based compounds using the Mycobacterium smegmatis aphVIII+ test system designed to screen for active STPKs inhibitors. First, we selected 53 compounds with subinhibiting concentrations of up to 100 nmol/disk. Of them, 22 showed STPKs-inhibiting activity in the test system, which was confirmed in vitro on the M. tuberculosis PknA protein with a maximum of 26.9 ± 6.1 %. Toxicity testing was performed in vitro on human embryo fibroblasts using the MTT-assay. Ultimately, 3 relatively active and relatively non-toxic STPKs inhibitors were selected for further research as drug candidates for MDR-TB treatment.

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Previously, we identified six serine/threonine protein kinases (STPK) of Bifidobacterium and named them Pkb1-Pkb6. In the present study, we optimized methods for isolation of the six STPK catalytic domains proteins of B. longum B379M: a method for isolation of Pkb3 and Pkb4 in native conditions, a method for isolation of Pkb5 in denaturing conditions, and a method for isolation of Pkb1, Pkb2, and Pkb6 from inclusion bodies. The dialysis conditions for the renaturation of the proteins were optimized. All of the enzymes were isolated in quantities sufficient for study of the protein activity. The proteins were homogeneous according to SDS-PAGE. The autophosphorylation ability of Pkb1, Pkb3, Pkb4, and Pkb6 was investigated for the first time. Autophosphorylation was detected only for the Pkb3 catalytic domain.