Abstract
The type III secretion system of Salmonella typhimurium directs the translocation of proteins into host cells. Evolutionarily related to the flagellar assembly machinery, this system is also present in other pathogenic bacteria, but its organization is unknown. Electron microscopy revealed supramolecular structures spanning the inner and outer membranes of flagellated and nonflagellated strains; such structures were not detected in strains carrying null mutations in components of the type III apparatus. Isolated structures were found to contain at least three proteins of this secretion system. Thus, the type III apparatus of S. typhimurium, and presumably other bacteria, exists as a supramolecular structure in the bacterial envelope.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Bacterial Outer Membrane Proteins / analysis
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Bacterial Proteins / analysis*
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Bacterial Proteins / chemistry
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Bacterial Proteins / metabolism*
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Bacterial Proteins / ultrastructure
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Cell Membrane / chemistry
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Cell Membrane / ultrastructure
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Centrifugation, Density Gradient
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Macromolecular Substances
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Membrane Proteins / analysis*
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Membrane Proteins / chemistry
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Membrane Proteins / ultrastructure
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Membrane Transport Proteins*
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Microscopy, Electron
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Microscopy, Immunoelectron
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Porins / analysis
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Salmonella typhimurium / chemistry*
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Salmonella typhimurium / metabolism
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Salmonella typhimurium / ultrastructure*
Substances
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Bacterial Outer Membrane Proteins
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Bacterial Proteins
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Macromolecular Substances
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Membrane Proteins
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Membrane Transport Proteins
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OmpF protein
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Porins
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PrgH protein, Salmonella typhimurium
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invG protein, Salmonella typhimurium