E. coli: What makes it kill?
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Integrated Bioinformatics • Comparison of genomes – Scenario • Regular expressions in Python • Installing and running Blast • How to find differences • Nature of research articles E. coli: What makes it kill? Escherichia coli . . . . . . very small lab rats Courtesy of Kent State University Microbiology E. coli: What makes it kill? Escherichia coli . . . • Shiga toxin-producing a.k.a. enterohemorrhagic E. coli (EHEC). • Enterotoxigenic E. coli • Enteropathogenic E. coli (EPEC) • Enteroaggregative E. coli (EAEC) • Enteroinvasive E. coli (EIEC) • Diffusely adherent E. coli (DAEC) At least six different dirarrheal "pathotypes" of E. coli ! http://www.cdc.gov/ecoli/general E. coli: What makes it kill? E. coli O157:H7 . . . The classic baddie!! • Shiga toxin-producing (STEC) a.k.a. enterohemorrhagic E. coli (EHEC) • First described as a pathogen in 1982 • The most prevalent in foodborne outbreaks • Most self-resolving diarrhea and vomiting • Hemolytic urinary syndrome a serious complication Easily the most extensively studied pathogenic E. coli E. coli: What makes it kill? E. coli O104:H4 . . . The up-and-comer • Enteroaggregative E. coli (EAEC) …but with acquired Shiga toxin genes! • First described as a pathogen in 2005 (only one case!), but caused a huge outbreak in Germany in 2011 • German outbreak traced back to sprouts! • 3,950 people affected, with 53 deaths, and 800 cases of hemolytic urinary syndrome Good example of how "new" pathogens can suddenly emerge Research papers Perna, N. T., G. Plunkett, 3rd, et al. (2001) Genome sequence of enterohaemorrhagic Escherichia coli O157:H7. Nature 409(6819): 529-33 Hayashi, T., K. Makino, et al. Complete genome sequence of enterohemorrhagic Escherichia coli O157:H7 and genomic comparison with a laboratory strain K-12. DNA Res 8(1): 11-22 Loman, et al. (2013). A culture-independent sequencebased metagenomics approach to the investigation of an outbreak of Shiga-toxigenic Escherichia coli O104:H4 JAMA 309(14): 1502-10 Hauser, et al. (2013). Phylogenetic and molecular analysis of food-borne shiga toxin-producing Escherichia coli. Appl Environ Microbiol. 79(8): 2731-40 E. coli: What makes it kill? E. coli K12 TCTACTTATA AAGAGTCTGT TTCTGTCTGC TGGATTTCGG GAACCTTAGT CTCCGTAAAC TGAATAAACT AAGAGTTTAA AAACCTGTAT TTATATATTT CCCCAGCTGT GACAGCACTG GCTGAAATTC CCCTGCACCA ATGAATGACT TTCAATCCAC TGAATGAACA TCTGACCTCT AACTCTAGCC GACTTCTGCT CTCTAACATG TTGTTAAAGG AGTTAAAAAC GGTTACATGA TAAGAAATTA CATTAAAAAG ACCCTCAAGA CGCTGAGAGC GGTCTTTCCT GAACGAACGA AGGGCTACAC CATACATGGT GGCAGCTTTC TGCCCCACTC ATACCAAAGT ATGTCAGCAA TACAAATGAA GAATTGCAGT ACTGCCTAAA ATTGCAATTA AGGCAAATAC AGGCACCGGC AGAGTGGTAC GTGGGCACTG TTGAATGAAA E. coli O157:H7 TCTACTTATA AAGAGTCTGT TTCTGTCTGC TGGATTTCGG GAACCTTAGT CTCCGTAAAC TGAATAAACT AAGAGTTTAA AAACCTGTAT TTATATATTT CCCCAGCTGT GACAGCACTG GCTGAAATTC CCCTGCACCA ATGAATGACT Gene finder TTCAATCCAC TGAATGAACA TCTGACCTCT AACTCTAGCC GACTTCTGCT CTCTAACATG TTGTTAAAGG AGTTAAAAAC GGTTACATGA TAAGAAATTA CATTAAAAAG ACCCTCAAGA CGCTGAGAGC GGTCTTTCCT GAACGAACGA AGGGCTACAC CATACATGGT GGCAGCTTTC TGCCCCACTC ATACCAAAGT ATGTCAGCAA TACAAATGAA GAATTGCAGT ACTGCCTAAA ATTGCAATTA AGGCAAATAC AGGCACCGGC AGAGTGGTAC GTGGGCACTG TTGAATGAAA Gene finder E. coli: What makes it kill? E. coli K12 TCTACTTATA AAGAGTCTGT TTCTGTCTGC TGGATTTCGG GAACCTTAGT CTCCGTAAAC TGAATAAACT AAGAGTTTAA AAACCTGTAT TTATATATTT CCCCAGCTGT GACAGCACTG GCTGAAATTC CCCTGCACCA ATGAATGACT TTCAATCCAC TGAATGAACA TCTGACCTCT AACTCTAGCC GACTTCTGCT CTCTAACATG TTGTTAAAGG AGTTAAAAAC GGTTACATGA TAAGAAATTA CATTAAAAAG ACCCTCAAGA CGCTGAGAGC GGTCTTTCCT GAACGAACGA AGGGCTACAC CATACATGGT GGCAGCTTTC TGCCCCACTC ATACCAAAGT ATGTCAGCAA TACAAATGAA GAATTGCAGT ACTGCCTAAA ATTGCAATTA AGGCAAATAC AGGCACCGGC AGAGTGGTAC GTGGGCACTG TTGAATGAAA E. coli O157:H7 TCTACTTATA AAGAGTCTGT TTCTGTCTGC TGGATTTCGG GAACCTTAGT CTCCGTAAAC TGAATAAACT AAGAGTTTAA AAACCTGTAT TTATATATTT CCCCAGCTGT GACAGCACTG GCTGAAATTC CCCTGCACCA ATGAATGACT Gene finder TTCAATCCAC TGAATGAACA TCTGACCTCT AACTCTAGCC GACTTCTGCT CTCTAACATG TTGTTAAAGG AGTTAAAAAC GGTTACATGA TAAGAAATTA CATTAAAAAG ACCCTCAAGA CGCTGAGAGC GGTCTTTCCT GAACGAACGA AGGGCTACAC CATACATGGT GGCAGCTTTC TGCCCCACTC ATACCAAAGT ATGTCAGCAA TACAAATGAA GAATTGCAGT ACTGCCTAAA ATTGCAATTA AGGCAAATAC AGGCACCGGC AGAGTGGTAC GTGGGCACTG TTGAATGAAA Gene finder E. coli: What makes it kill? Killer protein Killer functions Membrane protein, sodium transporter Iron responsive transcriptional regulator Calcium-dependent protein kinase Unknown protein Unknown protein Similarity finder Unknown protein ... Suggests therapeutic interventions How do these differences arise? How do genomic differences arise? Point mutation organism 1 TTT TCT GAA TCC GTA GAC GTT organism 2 TTT TCT GAA TCA GCA GAC GTG What kind of mutations arise? Can these explain the difference between K12 and O157:H7?? DNA mutation has multiple causes! • Errors during DNA replication • base mis-incorporation • polymerase slippage / repeat amplification • Errors during recombination or cell division • chromosome loss or rearrangement • large insertions or deletions • Environmental factors – mutagens: • radiation – UV or ionizing radiation • chemical – many mechanism of action • Spontaneous events: • tautomerisation • depurination • deamination • Viral infection or transposons How do genomic differences arise? Addition/deletion of DNA Where do they come from? How to distinguish – GC-content? from ? How do genomic differences arise? General transduction Infection Phage Phage genome Bacterial chromosome Lysogenic Phage genome pathway Lytic pathway = cell death! Lytic pathway How do genomic differences arise? General transduction Infection Phage Phage genome Bacterial chromosome Lysogenic Phage genome pathway Lytic pathway Lysogenic pathway = Life! How do genomic differences arise? General transduction Infection Phage Phage genome Bacterial chromosome Lysogenic Phage genome pathway Lytic pathway Lysogenic pathway = Life! Specialized transduction Occurs at defined sites Specialized transduction Occurs at defined sites The gene encoding diphtheria toxin (tox) is carried on corynephage b b tox – C.d. tox + C.d. Lysogenic conversion by corynephage b confers toxogenicity!!
