Document Detail

Domains of the Shigella flexneri type III secretion system IpaB protein involved in secretion regulation.
MedLine Citation:
PMID:  20937761     Owner:  NLM     Status:  MEDLINE    
Type III secretion systems (T3SSs) are key determinants of virulence in many Gram-negative bacterial pathogens. Upon cell contact, they inject effector proteins directly into eukaryotic cells through a needle protruding from the bacterial surface. Host cell sensing occurs through a distal needle "tip complex," but how this occurs is not understood. The tip complex of 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. It binds needles via its extreme C-terminal coiled coil, thereby likely positioning a large domain containing its hydrophobic regions at the distal tips of needles. In this study, we used short deletion mutants within this domain to search for regions of IpaB involved in secretion regulation. This identified two regions, amino acids 227 to 236 and 297 to 306, the presence of which are required for maintenance of IpaB at the needle tip, secretion regulation, and normal pore formation but not invasion. We therefore propose that removal of either of these regions leads to an inability to block secretion prior to reception of the activation signal and/or a defect in host cell sensing.
Da-Kang Shen; Saroj Saurya; Carolin Wagner; Hiroaki Nishioka; Ariel J Blocker
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2010-10-11
Journal Detail:
Title:  Infection and immunity     Volume:  78     ISSN:  1098-5522     ISO Abbreviation:  Infect. Immun.     Publication Date:  2010 Dec 
Date Detail:
Created Date:  2010-11-16     Completed Date:  2010-12-15     Revised Date:  2013-07-03    
Medline Journal Info:
Nlm Unique ID:  0246127     Medline TA:  Infect Immun     Country:  United States    
Other Details:
Languages:  eng     Pagination:  4999-5010     Citation Subset:  IM    
School of Cellular & Molecular Medicine, University of Bristol, Bristol BS8 1TD, United Kingdom.
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MeSH Terms
Antigens, Bacterial / genetics,  physiology
Bacterial Adhesion / physiology
Bacterial Proteins / physiology*
Bacterial Secretion Systems / genetics,  physiology*
Dysentery, Bacillary / microbiology*
Erythrocyte Membrane / microbiology
Gene Expression Regulation, Bacterial / genetics,  physiology
HeLa Cells
Microscopy, Fluorescence
Protein Structure, Tertiary / genetics,  physiology
Sequence Deletion / genetics
Shigella flexneri / genetics,  pathogenicity*
Grant Support
G0701243//Medical Research Council; K22AI001847/AI/NIAID NIH HHS
Reg. No./Substance:
0/Antigens, Bacterial; 0/Bacterial Proteins; 127384-62-7/ipaB protein, Shigella; 127384-63-8/IpaC protein, Shigella

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