| The extreme C terminus of Shigella flexneri IpaB is required for regulation of type III secretion, needle tip composition, and binding. | |
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MedLine Citation:
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PMID: 20086081 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Type III secretion systems (T3SSs) are widely distributed virulence determinants of Gram-negative bacteria. They translocate bacterial proteins into host cells to manipulate them during infection. The Shigella T3SS consists of a cytoplasmic bulb, a transmembrane region, and a hollow needle protruding from the bacterial surface. The distal tip of mature, quiescent needles is composed of IpaD, which is topped by IpaB. Physical contact with host cells initiates secretion and leads to assembly of a pore, formed by IpaB and IpaC, in the host cell membrane, through which other virulence effector proteins may be translocated. IpaB is required for regulation of secretion and may be the host cell sensor. However, its mode of needle association is unknown. Here, we show that deletion of 3 or 9 residues at the C terminus of IpaB leads to fast constitutive secretion of late effectors, as observed in a DeltaipaB strain. Like the DeltaipaB mutant, mutants with C-terminal mutations also display hyperadhesion. However, unlike the DeltaipaB mutant, they are still invasive and able to lyse the internalization vacuole with nearly wild-type efficiency. Finally, the mutant proteins show decreased association with needles and increased recruitment of IpaC. Taken together, these data support the notion that the state of the tip complex regulates secretion. We propose a model where the quiescent needle tip has an "off" conformation that turns "on" upon host cell contact. Our mutants may adopt a partially "on" conformation that activates secretion and is capable of recruiting some IpaC to insert pores into host cell membranes and allow invasion. |
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Authors:
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A Dorothea Roehrich; Isabel Martinez-Argudo; Steven Johnson; Ariel J Blocker; Andreas K J Veenendaal |
Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't Date: 2010-01-19 |
Journal Detail:
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Title: Infection and immunity Volume: 78 ISSN: 1098-5522 ISO Abbreviation: Infect. Immun. Publication Date: 2010 Apr |
Date Detail:
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Created Date: 2010-03-17 Completed Date: 2010-04-16 Revised Date: 2010-10-04 |
Medline Journal Info:
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Nlm Unique ID: 0246127 Medline TA: Infect Immun Country: United States |
Other Details:
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Languages: eng Pagination: 1682-91 Citation Subset: IM |
Affiliation:
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Departments of Cellular & Molecular Medicine, School of Medical Sciences, University of Bristol, University Walk, BS8 1TD Bristol, United Kingdom. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Bacterial Adhesion Bacterial Proteins / genetics*, metabolism* Gene Deletion Humans Membrane Transport Proteins / genetics*, metabolism* Models, Biological Mutant Proteins / genetics, metabolism Protein Binding Protein Interaction Mapping Sequence Deletion Shigella flexneri / pathogenicity* Virulence Factors / genetics*, metabolism* |
| Grant Support | |
ID/Acronym/Agency:
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082398//Wellcome Trust; G0400389//Medical Research Council; G0401595//Medical Research Council |
| Chemical | |
Reg. No./Substance:
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0/Bacterial Proteins; 0/Membrane Transport Proteins; 0/Mutant Proteins; 0/Virulence Factors; 127384-62-7/ipaB protein, Shigella |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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