Abstract
Bacterial type III protein secretion systems deliver effector proteins into eukaryotic cells in order to modulate cellular processes. Central to the function of these protein-delivery machines is their ability to recognize and secrete substrates in a defined order. Here, we describe a mechanism by which a type III secretion system from the bacterial enteropathogen Salmonella enterica serovar Typhimurium can sort its substrates before secretion. This mechanism involves a cytoplasmic sorting platform that is sequentially loaded with the appropriate secreted proteins. The sequential loading of this platform, facilitated by customized chaperones, ensures the hierarchy in type III protein secretion. Given the presence of these machines in many important pathogens, these findings can serve as the bases for the development of novel antimicrobial strategies.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Sequence
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Antigens, Bacterial / chemistry
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Antigens, Bacterial / metabolism
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Bacterial Proteins / chemistry
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Bacterial Proteins / metabolism*
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Bacterial Secretion Systems / physiology*
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Cytoplasm / metabolism
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Membrane Proteins / chemistry
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Membrane Proteins / metabolism*
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Molecular Chaperones / chemistry
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Molecular Chaperones / metabolism*
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Molecular Sequence Data
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Multiprotein Complexes / metabolism
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Mutation
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Protein Binding
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Protein Transport
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Salmonella typhimurium / genetics
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Salmonella typhimurium / metabolism*
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Salmonella typhimurium / pathogenicity*
Substances
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Antigens, Bacterial
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Bacterial Proteins
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Bacterial Secretion Systems
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Membrane Proteins
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Molecular Chaperones
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Multiprotein Complexes
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OrgA protein, Salmonella typhimurium
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Salmonella invasion protein C
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SpaO protein, Salmonella sp.
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SspD protein, Salmonella typhimurium
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invasion protein B, Salmonella typhimurium