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Type III secretion effectors in bacterial genome

Type III secretion effectors in bacterial genome. 5 May 2010 Sūn Guăng Wén Biochemistry, NUS. Melioidosis. Causative agent: Burkholderia pseudomallei Endemic area: SEA; northern Australia Symptom: variable Diagnosis: Serum test, culture of bacteria, PCR

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Type III secretion effectors in bacterial genome

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  1. Type III secretion effectors in bacterial genome 5 May 2010 Sūn Guăng Wén Biochemistry, NUS

  2. Melioidosis Causative agent: Burkholderia pseudomallei Endemic area: SEA; northern Australia Symptom: variable Diagnosis: Serum test, culture of bacteria, PCR Risk factor: Type II diabetes and kidney failure Treatment: Ceftazidime Vaccine: not available

  3. Burkholderia pseudomallei • Facultative anaerobic, • in soil and surface water • Opportunistic pathogen • Resistant to many antibiotics • Huge genome: 4.1Mb +3.2Mb • Many virulence factors: siderophore, flagella, T3SSs, T6SSs • Able to invade cells and survive intracellularly

  4. Type III secretion system (T3SS) SPI I of Salmonella

  5. T3SS and flagella

  6. Distribution of T3SSs among pathogenic bacteria Nat rev MCB 3:743

  7. T3 Effectors modify host signaling pathways

  8. Effectors mimic host protein function

  9. Effectors can introduce covalent-modification

  10. Effectors are less conserved

  11. N-terminal of effector contains secretion signal N-ter signal reporter Fusion assay

  12. Determination of secretion signal http://www.effectors.org/ ---very high false positive rate! PLoS Pathogens April 2009 | Volume 5 | Issue 4 | e1000376

  13. Signal is more defined within a species

  14. Inv/mxi/spa-like T3S3 of B. pseudomallei Translocons Secreted effectors Base and inner membrane complex Regulator Molecular Microbiology (2002) 46(3), 649–659 Molecular Microbiology (2010) 76(3), 677–689 Chaperone

  15. Burkholderia pseudomallei genome Burkholderia pseudomallei K96243: NC_006350; NC_006351 , http://www.ncbi.nlm.nih.gov/sutils/genom_table.cgi http://www.sanger.ac.uk/cgi-bin/blast/submitblast/b_pseudomallei

  16. The challenge: To identify T3S3 effectors in bp genomes • Define training sets, collect effector sequences • Find patterns in N-terminals • Search Burkholderia pseudomallei genomes • Blast top hits in protein databases • Verify through experiments

  17. Assembly of T3S needle

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