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Pathogenomics

Pathogenomics. Goal: Identify previously unrecognized mechanisms of microbial pathogenicity using a unique combination of informatics, evolutionary biology, microbiology and genetics. Pathogenicity. Processes of microbial pathogenicity at the molecular level are still minimally understood

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Pathogenomics

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  1. Pathogenomics Goal: Identify previously unrecognized mechanisms of microbial pathogenicity using a unique combination of informatics, evolutionary biology, microbiology and genetics.

  2. Pathogenicity • Processes of microbial pathogenicity at the molecular level are still minimally understood • Pathogen proteins identified that manipulate host cells by interacting with, or mimicking, host proteins. • Idea: Could we identify novel virulence factors by identifying pathogen genes more similar to host genes than you would expect based on phylogeny?

  3. Eukaryotic-like pathogen genes Aquifex aeolicus 96 - YopH, a protein-tyrosine phosphatase, of Yersinia pestis - Enoyl-acyl carrier protein reductase (involved in lipid metabolism) of Chlamydia trachomatis Haemophilus influenza 100 Escherichia coli Anabaena 100 Synechocystis 100 Chlamydia trachomatis 63 Petunia x hybrida 64 Nicotiana tabacum 83 Brassica napus 99 Arabidopsis thaliana 0.1 52 Oryza sativa

  4. Approach Screen for candidate genes. Search pathogen genes against sequence databases. Identify those with eukaryotic similarity/motifs • Rank candidates. • how much like host protein? • info available about protein? Modify screening method /algorithm Evolutionary significance. - Horizontal transfer? Similar by chance? • Prioritize for biological study. • - Previously studied biologically? • Can UBC microbiologists study it? • C. elegans homolog?

  5. Pathogens Anthrax Necrotizing fasciitis Cat scratch disease Paratyphoid/enteric fever Chancroid Peptic ulcers and gastritis Chlamydia Periodontal disease Cholera Plague Dental caries Pneumonia Diarrhea (E. coli etc.) Salmonellosis Diphtheria Scarlet fever Epidemic typhus Shigellosis Mediterranean fever Strep throat Gastroenteritis Syphilis Gonorrhea Toxic shock syndrome Legionnaires' disease Tuberculosis Leprosy Tularemia Leptospirosis Typhoid fever Listeriosis Urethritis Lyme disease Urinary Tract Infections Meliodosis Whooping cough Meningitis +Hospital-acquired infections

  6. Pathogens Chlamydophila psittaci Respiratory disease, primarily in birds Mycoplasma mycoides Contagious bovine pleuropneumonia Mycoplasma hyopneumoniae Pneumonia in pigs Pasteurella haemolytica Cattle shipping fever Pasteurella multicoda Cattle septicemia, pig rhinitis Ralstonia solanacearum Plant bacterial wilt Xanthomonas citri Citrus canker Xylella fastidiosa Pierce’s Disease - grapevines Bacterial wilt

  7. Approach Prioritized candidates Study function of gene. Investigate role of bacterial gene in disease: Infection study in model host Study function of similar gene in model host, C. elegans. Contact other groups for possible collaborations. C. elegans DATABASE World Research Community

  8. Interdisciplinary group • Informatics/Bioinformatics • BC Genome Sequence Centre • Centre for Molecular Medicine and Therapeutics • Evolutionary Theory • Dept of Zoology • Dept of Botany • Canadian Institute for Advanced Research Coordinator • Pathogen Functions • Dept. Microbiology • Biotechnology Laboratory • Dept. Medicine • BC Centre for Disease Control • Host Functions • Dept. Medical Genetics • C. elegans Reverse Genetics Facility • Dept. Biological Sciences SFU

  9. Power of the Approach • Interdisciplinary team unique ideas and collaborations • Automated approach continually updated • Better understanding: pathogen gene and similar host gene • Insight into horizontal gene transfer events and the evolution of pathogen-host interactions. • Public database • other researchers may capitalize on the findings • promote further collaboration

  10. Database front end

  11. PhyloBLAST – a tool for the analysis

  12. Bacillus subtilis Escherichia coli Salmonella typhimurium Staphylococcua aureus Clostridium perfringens Clostridium difficile Trichomonas vaginalis Haemophilus influenzae Acinetobacillus actinomycetemcomitans 0.1 Pasteurella multocida Bacterium Eukaryote Horizontal Transfer N-acetylneuraminate lyase (NanA) of the protozoan Trichomonas vaginalis is 92-95% similar to NanA of Pasteurellaceae bacteria.

  13. N-acetylneuraminate lyase (sialic acid lyase, NanA) Hydrolysis of glycosidic linkages of terminal sialic residues in glycoproteins, glycolipids Sialidase Free sialic acid Transporter Free sialic acid NanA N-acetyl-D-mannosamine + pyruvate Intracellular enzyme involved in sialic acid metabolism In Bacteria: Proposed to parasitize the mucous membranes of animals for nutritional purposes

  14. N-acetylneuraminate lyase – role in pathogenicity? • Pasteurellaceae • Mucosal pathogens of the respiratory tract • Intracellular NanA enzyme with sialic acid transporter • T. vaginalis • Mucosal pathogen, causative agent of the STD Trichomonas • Extracellular enzyme, so avoids need for transporter?

  15. Eukaryote Bacteria Horizontal Transfer? Rat 0.1 Guanosine monophosphate reductase of E. coli is 81% similar to the corresponding enzyme studied in humans and rats, and shares a significant phylogenetic relationship with metazoans (left). Its role in virulence has not been investigated. Human Escherichia coli Caenorhabditis elegans Pig roundworm Methanococcus jannaschii Methanobacterium thermoautotrophicum Bacillus subtilis Streptococcus pyogenes Aquifex aeolicus Acinetobacter calcoaceticus Haemophilus influenzae Chlorobium vibrioforme

  16. Hypocrea jecorina EGLII Trichoderma viride EGL2 Penicillium janthinellum EGL2 Macrophomina phaseolina EGL2 Cryptococcus flavus CMC1 Ralstonia solanacearum egl Humicola insolens CMC3 Humicola grisea CMC3 Aspergillus aculeatus CMC2 Aspergillus nidulans EGLA Macrophomina phaseolina egl1 Aspergillus aculeatus CEL1 Aspergillus niger EGLB Vibrio species manA Eukaryote Bacteria Horizontal Transfer? Ralstonia solanacearum cellulase (ENDO-1,4-BETA-GLUCANASE) is 56% similar to endoglucanase present in a number of fungi. Demonstrated virulence factor for plant bacterial wilt

  17. Trends in the Analysis • Most cases of probable recent cross-domain gene transfer involve movement of a bacterial gene to a unicellular eukaryote • Identifies the strongest cases of lateral gene transfer between bacteria and eukaryotes • A control: The method identifies all previously reported Chlamydia trachomatis eukaryotic-like genes.

  18. G+C Analysis: Identifying Pathogenicity Islands %G+C S.D. Location Strand Gene Product 52.24 879443..880738 - NMB0854 histidyl-tRNA synthetase 46.42 880832..881488 - NMB0855 put. bacteriocin resist. 26.07 -2 881770..882237 - NMB0856 hypothetical protein 37.29 -1 882294..882470 - NMB0857 hypothetical protein 42.29 -1 882474..882674 - NMB0858 hypothetical protein 29.37 -2 882677..883054 - NMB0859 hypothetical protein 35.27 -2 883112..883369 - NMB0860 hypothetical protein 47.99 883459..884004 - NMB0861 hypothetical protein 35.00 -2 884001..884120 - NMB0862 hypothetical protein 26.37 -2 884167..884439 - NMB0863 hypothetical protein 33.33 -2 884705..884995 - NMB0864 hypothetical protein 47.05 885001..885474 - NMB0865 hypothetical protein 53.33 885517..886386 - NMB0866 hypothetical protein 52.38 886550..887473 + NMB0867 YabO/YceC/SfhB fam. prot. 57.63 887551..888192 - NMB0868 conserved hypothetical 54.42 888247..889038 - NMB0869 hypothetical protein 55.56 889531..890322 + NMB0870 3-methyl-2-oxobutanoate hydroxymethyltransferase

  19. G+C of ORFs: Analysis of Variance • Low G+C variance correlates with an intracellular lifestyle for the bacterium and a clonal nature (P = 0.004) • This variance is similar within a given species • Useful marker for investigating the clonality of bacteria? Relationship with intracellular lifestyle may reflect the ecological isolation of intracellular bacteria?

  20. Future Developments • Incorporate unfinished genomes, plasmids into analysis (including eukaryotic) • Motif-based and domain-based analyses • G+C analysis graphical viewer for identification of pathogenicity islands • Functional tests

  21. Peter Wall Foundation • Pathogenomics group • Ann M. Rose, Yossef Av-Gay, David L. Baillie, Fiona S. L. Brinkman, Robert Brunham, Stefanie Butland, Rachel C. Fernandez, B. Brett Finlay, Hans Greberg, Robert E.W. Hancock, Christy Haywood-Farmer, Steven J. Jones,Patrick Keeling, Audrey de Koning, Don G. Moerman, Sarah P. Otto, B. Francis Ouellette, Ivan Wan. www.pathogenomics.bc.ca

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