Methods of Secretion

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Methods of Secretion
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Protein Secretion
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Type II Secretion (GEP)

• Sec dependent
• Signal peptide
• Chaperone
• 2 Stage
• E.g IgA-protease, Pertussis toxin,
• Serratia haemolysin

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General Secretion Pathway (Type II)
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Type IIExport
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Type I Secretion

• Sec independent
• ABC (ATP Binding Cassette)
• COOH recognition peptide
• 1 Stage
• E.g cytolysins, hydrolases,
• B. pertussis adenylate cyclase

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Type III Secretion
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Type III Secretion

• Sec independent
• Secretion co-translational
• Translocation into host cell
• Polar or non-polar secretion
• E.g Yersinia spp. Yops, Shigella IpaB, C D
  EPEC EspA, B, C, Tir

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Paradigms of Host-Cell Interactions I
Enterobacter

• Vibrio cholera
• E coli spp.
• Shigella spp.

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Cholera
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Enteropathic E coli

• Serotypes and serogroups e.g O111H4,O111H12
• Virotypes ETEC EAggEC
• EPEC EHEC
• EIEC

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ETEC

• Similar to V. cholera in symptoms and
  colonization
• Causes Travellers Diarrhea
• Two toxins heat-labile (LT) and heat-stable(ST)

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EAGGEC

• Causes persistent diarrhea
• Resembles ETEC in colonization except that
  adherence to small intestinal cells non-uniform.
• Produce ST-like toxin and hemolysin-like toxin.

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EPEC

• Like EAGGEC, adherence also in clumps.
• Causes attachment and effacement lesions.
• More invasive than ETEC or EAGGEC
• Induces inflammatory response.

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EHEC

• Can cause acute kidney failure (hemolytic-uremic
  syndrome HUS)
• Disease similar to that of Shigella dysentary.

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EIEC

• Symptoms similar to Shigella dysentary.
• Actively invades colonic cells with adjacent
  spread like Shigella, although no toxin produced.

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Shigella
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ShigellaIcs (Intercellular Spread)
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Shigella Virulence Genes