International conference on bioinformatics of genome regulation
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Key words: DNA damage, DNA repair, protein design, formamidopyrimidine–DNA glycosylase Motivation and Aim: DNA glycosylases are enzymes that remove modified bases from DNA and are a key element of base excision DNA repair. Due to their ability to cleave DNA at defined modified nucleotides, these enzymes are now finding use as tools in mo- lecular biology, biotechnology and bioanalytics. Thus, design of DNA glycosylases with altered substrate specificities is of great primary fundamental and practical interest. In particular, bacterial formamidopyrimidine–DNA glycosylase (Fpg) removes 8-oxogua- nine (oxoG) and formamidoptrimidines from DNA, and has a base-binding site built of a tetrapeptide loop. In this work we aim to design DNA glycosylases that will be able to recognize other nucleobases (e. g., 6-thioguanine, thioG, an important antiproliferative drug that acts through incorporation into DNA), on the protein scaffold of Fpg. Methods and Algorithms: We have used molecular dynamics modeling to analyze a sample of 102 randomly mutagenized Fpg base-binding loops built into otherwise intact Fpg scaffold to compare several estimators of “closeness” of the mutant sequences to wild-type Fpg. Additionally, using quantum mechanical calculations, we have analyzed the mechanism of N-glycosidic bond cleavage in solution for several purine nucleotides structurally related to G and oxoG. Results: In the Fpg molecule, the site of substrate recognition and the catalytic center are separated in space. The active site contains invariant Pro1 and Glu2 residues and some highly conserved residues that form contacts with phosphates in DNA. In the substrate recognition site, a loop of four amino acid residues binds the O 6 atom of 8-oxoguanine, with the static structure not particularly informative of the enzyme’s base specificity. We constructed 102 structures of Fpg/8-oxoguanine–DNA complexes where this tetrapep- tide was randomly changed and analyzed them by molecular dynamics. On the basis of the local geometry ranking, the function of model quality was built, which determines the multidimensional distance between the conformation of the active site of mutant Fpg and the catalytically competent conformation of the active site of wild-type Fpg. This function will be further used to predict the ability of random-loop Fpg structures to rec- ognize other purines, including thioG. Several algorithms of walk in the sequence space to minimize the number of computationally expensive models have been compared. Conclusion: We propose a scheme for rational design of DNA glycosylases with altered substrate specificity based on the Fpg scaffold. This approach will be used to construct enzymes able to cleave DNA at modified purine lesions, in particular, thioG. This work was supported by Russian Science Foundation (14-24-00093). 347 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY IN SILICO DESIGN OF APTAMERS CONTAINING G-QUADRUPLEXES A.O. Zalevsky 1,2 *, A.O. Demkiv 2 , A.V. Golovin 1, 2 1 Apto-Pharm LLC, Moscow, Russia 2 Faculty of bioengineering and bioinformatics, Lomonosov Moscow State University, Moscow, Russia * Corresponding author: aozalevsky@fbb.msu.ru Key words: aptamers, molecular dynamics, rational design, g-quadruplex Motivation and Aim: Aptamers are promising molecules for therapy and diagnostics. DNA-made aptamers combine high specificity of monoclonal antibodies with low im- mune response and ease of production [1]. However despite of all possible advantages aptamers are still not as widespread as one could thought. Major limitation related to complicated aptamers tuning process. Knowledge of aptamer’s structure is crucial for succesfull optimiziations but due to nature of SELEX pipeline (method for obtaining aptamers), it is usually unknown. Here we try to use computational approaches to overcome typical SELEX limitations and design G-quadruplex containing aptamers. G-quadruplexes are known for their in- creased stability compared to duplex analogs [2]. Methods and Algorithms: Our approach combines several methods for molecular mod- eling such as molecular docking (AutoDock Vina) and molecular dynamics (Gromacs). All tools are integrated in one pipeline written in Python with critical parts being opti- mized (Cython) and parallelized (MPI). Experimental validation of G-quadruplex pres- ence is done with circular dichroism spectroscopy and binding to target is tested with capillar electrophoresis. Results: For testing purposes, we applied our approach to thrombin. After several rounds of ranking and filtration, several candidates with relatively stable structures and pre- served designed protein-dna contacts were selected and tested experimentally. Conclusion: Here we present new computational approach for in silico design of aptam- ers containing G-quadruplexes based solely on target’s 3D structure. Availability: Acknowledgements: This study was supported by the Russian Foundation for Basic Re- search project no. 16-34-01362. Computations were done at the supercomputer systems “Lomonosov” and “Lomonosov-2” of Lomonosov Moscow State University, Moscow, Russia. References: 1. H. Sun et al. (2014), Oligonucleotide Aptamers: New Tools for Targeted Cancer Therapy, Molecular Therapy Nucleic Acids, 3: e182. 2. A.Lane et al. (2008) Stability and kinetics of G-quadruplex structures, JNucleic Acid Research, 36: 5482–5515. 348 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY DISTINCT TYPES OF EIN3-DNA INTERACTIONS IN VARIOUS FUNCTIONAL REGIONS OF A. THALIANA L. GENOME E.V. Zemlyanskaya 1, 2 *, D.Yu. Oshchepkov 1 , V.G. Levitsky 1, 2 1 Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia 2 Novosibirsk State University, Novosibirsk, Russia * Corresponding author: ezemlyanskaya@bionet.nsc.ru Key words: transcription factor, ethylene insensitive 3 (EIN3), ChIP-seq data analysis Motivation and Aim: Plant hormone ethylene regulates a wide range of physiological processes during plant development and coordinates different stress responses [1]. Tran- scription factor (TF) EIN3 is a master regulator of ethylene signaling pathway [2]. The emergence of chromatin immunoprecipitation followed by genome-wide sequencing (ChIP-Seq) stimulated the description and characterization of motifs for many transcrip- tion factors. Availability of the whole-genome maps of chromatin types and TF binding sites derived from ChIP-seq data allows finer characterization of TF-DNA interactions. We use these data to investigate EIN3-DNA interactions to reveal details of EIN3 action. Methods and Algorithms: We analyzed ChIP-seq data for EIN3 binding in Arabidopsis thaliana [2]. DNA motifs, specific for certain types of A. thaliana chromatin [3], were identified with Homer tool [4] for de novo motif search. Results: We found the heterogeneity of peaks distribution in gene promoters at various distances from transcription start sites (TSS), within bodies of genes, in introns and intergenic spacers. EIN3 peaks were enriched within 300 bp upstream TSS and in in- tergenic spacers. To finer characterize EIN3-DNA interactions, we distinguished EIN3 peaks located in chromatin domains of states 2 and 4 [3]. In [3] these domains were re- ferred to as proximal and distant 5’regulatory regions of genes. The nucleotide context of EIN3 binding sites was more conserved in distant chromatin domains than in proximal ones. De novo motif search in close proximity to EIN3 motifs revealed several distinct motifs in proximal and distant chromatin domains. We believe that they represent bind- ing sites for EIN3 partner TFs. We found essential difference between the sets of partner TFs corresponding to different types of chromatin domains. Conclusion: EIN3 regulation of gene expression is mediated by at least “proximal” and “distant” types of EIN3-DNA interactions. Acknowledgements: The work was supported by RFBR 15-34-20870. References: 1. F.B. Abeles et al. (1992) Ethylene in plant biology. San Diego: Acad. Press. 2. K.N. Chang et al. (2013) Temporal transcriptional response to ethylene gas drives growth hormone cross-regulation in Arabidopsis. Elife, 2:e00675. 3. J. Sequeira-Mendes et al. (2014) The functional topography of the Arabidopsis genome is organized in a reduced number of linear motifs of chromatin states. Plant Cell, 26: 2351–2366. 4. S. Heinz et al. (2010) Simple combinations of lineage-determining transcription factors prime cis- regulatory elements required for macrophage and B cell identities. Mol Cell, 38:576-589. 349 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY ELEMENTAL METABOLOMICS – LINKING ENVIRON- MENTAL, FOOD, NUTRITION AND HEALTH SCIENCES P. Zhang 1 , I. Giannenas 2 , C.A. Georgiou 3 , V. Brusic 1, 4 * 1 Menzies Health Institute Queensland, Griffith University, Australia 2 Aristotle University of Thessaloniki, Thessaloníki, Greece 3 Department of Food Science and Nutrition, Agricultural University of Athens, Greece 4 School of Medicine and Bioinformatics Center, Nazarbayev University, Kazakhstan * Corresponding author: vladimir.brusic@nu.edu.kz; v.brusic@griffith.edu.au Key words: elemental signatures, metabolome, metallomics, mineralomics, ionomics Motivation and Aim: The advancements in instrumentation, measurement methods, and standards in mass spectrometry enabled us to precisely measure the quantities of more than 70 trace and ultra-trace elements (measurable elements) in biological materials. Very recently, the precision of measurements and lower cost enabled us to measure el- emental matrices on a large scale. Measurable elements are bioavailable from the envi- ronment, including air, water, and soil from where they are absorbed and accumulated by plants. Measurable elements enter animal and human bodies through environmental exposure or through food chain. Elemental metabolome profiles can be used for identi- fication of environmental exposure, food authentication, effects of nutritional interven- tion, food quality assessment, and health monitoring. Methods: Two studies were performed. Samples of three sets of chicken eggs (con- ventionally grown, organic, and free-range) were measured for elemental profiles of 12 trace elements (As, Cd, Co, Cr, Cu, Mn, Mo, Ni, Se, Tl, V, and Zn). The comparison of elemental profiles was used to classify eggs by the production system. These data were compared with the eggs of another four species (turkey, goose, duck, and pigeon) that were given exactly the same diet as was given to the courtyard chickens. Results: Elemental profiles enabled highly accurate classification of eggs by production method. Using sensitivity and specificity measures we assessed classification accuracy to be SE=0.958, SP=0.99 (conventional); SE=0.979, SP=0.979 (organic); and SE=1.0, SP=1.0 (free-range). The comparison with elemental profiles of other species has shown that chicken egg elemental profiles are more similar to other chicken eggs elemental profiles than to those representing eggs of other species, irrespective of the production system applied. Conclusion: Elemental metabolomics provides a new method suitable for biomonitor- ing. It can be used for classification of samples by their origin (geographic, production system, genetic origin), nutritional status, or health status. 350 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY SPEED READING AT THE MOLECULAR SCALE: HOW ENZYMES FIND TYPOS IN A DNA TEXT D.O. Zharkov* Institute of Chemical Biology and Fundamental Medicine SB RAS, Novosibirsk, Russia * Corresponding author: dzharkov@niboch.nsc.ru Key words: DNA damage, DNA repair, substrate specificity, target search Motivation and Aim: Many enzymes involved in genome surveillance, maintenance and editing face a task of finding rare targets within a huge excess of non-specific DNA. Such targets may represent specific DNA sequences, either exactly defined or consensu- al, or modified nucleotides, or non-canonical DNA structures. There is always a trade-off between the rate of search and the rate of errors (not recognizing a target or mistakenly accepting a non-target), with the errors possibly bearing a huge cost for the cell (1–3). The mechanisms by which DNA-dependent enzymes achieve an optimal balance be- tween speed and fidelity are largely obscure. Methods and Algorithms: We have used a combination of methods including molecular modeling, fast enzyme kinetics, DNA and protein melting, and solution NMR to address the mechanisms underlying search and recognition of damaged bases by several DNA repair enzymes: DNA glycosylases and abasic site endonucleases. Results: DNA repair enzymes search for their targets by fast one-dimensional scanning along the DNA contour intermittent with rare events of transfer to another site remote in 1D but close in 3D relative to the current location. This search is facilitated by extended N- or C-terminal domains present in some repair enzymes and apparently evolved from rapidly diverged short sequence repeats. The one-dimensional scanning function may sometimes be exploited for other purposes, such as uracil–DNA glycosylases adopted as DNA polymerase processivity factors by some viruses. The enzymes first probe DNA indirectly, relying on DNA deformability for the primary damage assessment. Once a “soft spot” is found, the sampled base is everted from the double helix stack, with several energy barriers along the eversion pathway allowing the enzyme to reject normal bases. Recognition within the active site contributes little to the specificity, with the rate of the chemical step mostly dependent on the interactions with DNA moieties other than the sampled base. Conclusion: DNA repair enzymes find optimum between speed and fidelity through multigated recognition of the lesion, which allows for kinetic competition between dif- fusion and productive substrate encounters. This work was supported by Russian Science Foundation (14-24-00093) References: 1. D.O. Zharkov, A.P. Grollman (2005) The DNA trackwalkers: Principles of lesion search and recogni- tion by DNA glycosylases, Mutat. Res., 577: 24-54. 2. D.O. Zharkov, G.V.Mechetin, G.A.Nevinsky (2010) Uracil-DNA glycosylase: Structural, thermody- namic and kinetic aspects of lesion search and recognition. Mutat. Res., 685: 11-20. 3. G.V. Mechetin, D.O.Zharkov (2014) Mechanisms of diffusional search for specific targets by DNA- dependent proteins. Biochemistry (Mosc.), 79: 496-505. 351 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY PHYLOGENETIC RECONSTRUCTION WITHIN MYCOBACTERIUM TUBERCULOSIS BEIJING GENOTYPE IN NORTHEASTERN RUSSIA S. Zhdanova 1 *, O. Ogarkov 1, 2, 3 , G. Alexeeva 4 , M. Vinikurova 4 , E. Savilov 1, 2 , V. Sinkov 1 1 Scientific Centre of the Family Health and Human Reproduction Problems, Irkutsk, Russia 2 Irkutsk State Medical Academy of Continuing Education, Irkutsk, Russia 3 Irkutsk State University, Irkutsk, Russia 4 Research Practice Center for Phthisiatry, Yakutsk, Russia * Corresponding author: svetnii@mail.ru Key words: M. tuberculosis, MIRU-VNTR, epidemic subtypes, Beijing Motivation and objectives: Mycobacterium tuberculosis Beijing strains cause wide con- cern because of their speedy emergence and increasing prevalence in world. The phylo- genetic reconstruction of Beijing strains evolution within territory with limited migra- tion could provide us a model to understand the dynamics of some epidemic subtypes expansion. Methods and Algorithms: We used 153 stains to compare the population structures of the M. tuberculosis between different birth-year cohorts of patients in Sakha (Yakutia). MIRU-VNTR genotyping, RD105/RD207 subtyping [1], classification of patterns on clonal complexes Merker M. et al. [2] and phylogenetic modeling were implemented. Profiles of 153 strains of the 24th MIRU-VNTR loci using MS Excel 2007 have been converted to a binary format and used to construct NJ tree, programs Ugene [3] and FigTree [4]. Results: The structure of the population of Mycobacterium tuberculosis and shift that occurred during the previous fifty years have been described and analyzed. The results revealed that the spread of modern subtype of Beijing genotype that have high transmis- sibility and multiply drug resistance currently in Russia, is significantly higher in young (post-1990 birth) than in the older generation (born before 1959) (χ 2 =8.3, p<0.01). The hypothesis of later emergence of epidemic subtypes genotype Beijijng in the Sakha (Ya- kutia) than in other regions of Russia (around fifty years ago) is substantiated. Acknowledgements: This work has been supported by grant from RFBR #15-04-00632 А References: 1. M. Reed et al. (2009). Major Mycobacterium tuberculosis Lineages Associate with Patient Country of Origin, J. Clin. Microbiol, 47(4): 1119-1128. 2. M. Merker et al. (2015). Evolutionary history and global spread of the Mycobacterium tuberculosis Beijing lineage, Nat Genet., 47(3): 242-249. 3. K.Okonechnikov et al. (2012). Unipro UGENE: a unified bioinformatics toolkit, Bioinformatics, 28: 1166-1167. 4. V.I. Morariu et al (2008). Automatic online tuning for fast Gaussian summation. Advances in Neural Information Processing Systems. V. 21. P.1113-1120. 352 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY CHEMORESISTANCE OF LUNG ADENOCARCINOMA IS REGULATED BY TUDOR STAPHYLOCOCCAL NUCLEASE B. Zhivotovsky 1, 2 1 Lomonosov Moscow State University, Moscow, Russia 2 Karolinska Institutet, Stockholm, Sweden * Corresponding author: Boris.Zhivotovsky@ki.se Key words: cancer, gene expression, gene networks, pathway analysis Lung cancer is the main cause of all cancer-related deaths in the world, with lung ad- enocarcinoma (ADC) being the most common subtype of this fatal disease. Lung ADC is often diagnosed at advanced stages involving disseminated metastatic tumors. This is particularly important for the successful development of new cancer therapy approaches. The high resistance of lung ADC to conventional radio- and chemotherapies represents a major challenge to treatment effectiveness. Earlier we found that Tudor staphylococcal nuclease (SND1 or TSN) is overexpressed in ADC lines and tissues, and is important for maintaining of ADC chemoresistance. Downregulation of TSN by RNAi in ADC cells led to strong potentiation of cell death in response to cisplatin. In order to identify potential molecular targets involved in ADC sensitization to cis- platin, the global gene expression analysis was performed. Widespread transcriptional changes were observed upon TSN knockdown: 391 unique genes demonstrated a greater than twofold average change in expression, with 234 transcripts under- and 157 tran- scripts overexpressed compared to scrambled transfected control samples. Using the Ingenuity Pathways Analysis (IPA) program and gene ontology category enrichment analyses, we selected several major networks containing genes that were closely associ- ated with autophagy and apoptotic cell death as well as survival, DNA damage response and Ca 2+ signaling. The expression of shortlisted genes was further analyzed by q-RT- PCR, confirming microarray data. ON the top of the list was S100A11. Silencing of TSN was accompanied by a significant decrease in S100A11 expression at both mRNA and protein level. Downregulation of S100A11 by RNAi resulted in enhanced sensitivity of NSCLC cells to cisplatin, oxaliplatin and 5-fluouracil. S100A11 interactions were analyzed using Interactive pathway analysis of complex’omics data and S100A11-related pathways involved in apoptosis and cell resistance to cytotox- ic treatment were selected for further analysis. We found that in cell cytoplasm S100A11 interacts with Annexin A1 and Annexin A2 and inhibit phospholipases A 2 (PLA 2 ), a su- perfamily of enzymes involved in arachidonic acid (AA) release. A PLA 2 inhibitor or silencing with siRNA strongly abrogated chemosensitization upon silencing of S100A11 suggesting that PLA 2 inhibition by S100A11 governs the chemoresistance of ADCs. Thus, we present the novel TSN-S100A11-PLA 2 axis regulating superoxide-dependent apoptosis, triggered by platinum-based chemotherapeutic agents in ADCs that may be targeted by innovative cancer therapies. This study was supported by grant from the Russian Science Foundation (14-25-00056). 353 THE TENTH INTERNATIONAL CONFERENCE ON BIOINFORMATICS OF GENOME REGULATION AND STRUCTURE\SYSTEMS BIOLOGY COMPUTER SIMULATION OF TRICHOME PATTERNING ON GROWING WHEAT LEAF TAKING INTO ACCOUNT THE BIOMECHANICS OF CELLS U.S. Zubairova 1 *, S.V. Nikolaev 1 , A.V. Penenko 2 , N.L. Podkolodnyy 1 , S.K. Golushko 3 , D.A. Afonnikov 1 , N.A. Kolchanov 1 1 Institute of Cytology and Genetics SB RAS, Novosibirsk, Russia 2 Institute of Computational Mathematics and Mathematical Geophysics SB RAS, Novosibirsk, Russia 3 Design and Technology Institute of Digital Techniques SB RAS, Novosibirsk, Russia * Corresponding author: ulyanochka@bionet.nsc.ru Download 3.91 Kb. Do'stlaringiz bilan baham: |
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