Document Detail


Energy-dependent changes in the gonococcal transferrin receptor.
MedLine Citation:
PMID:  9383187     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The pathogenic Neisseria spp. are capable of iron utilization from host iron-binding proteins including transferrin and lactoferrin. Transferrin iron utilization is an energy-dependent, receptor-mediated event in which two identified transferrin-binding proteins participate. One of these proteins, TbpA, is homologous to the TonB-dependent family of outer membrane receptors that are required for high-affinity uptake of vitamin B12 and ferric siderophores. The 'TonB box' is a conserved domain near the amino-terminus of these proteins that has been implicated in interaction with TonB. Interaction between a periplasmic domain of TonB and the TonB box allows energy transduction to occur from the cytoplasmic membrane to the energy-dependent receptor in the outer membrane. We created a TonB box mutant of gonococcal TbpA and demonstrated that its binding and protease accessibility characteristics were indistinguishable from those of gonococcal Ton system mutants. The protease exposure of the second transferrin-binding protein, TbpB, was affected by the energization of TbpA, consistent with an interaction between these proteins. TbpB expressed by the de-energized mutants was readily accessible to protease, similar to TbpB expressed in the absence of TbpA. The de-energized mutants exhibited a marked decrease in transferrin diffusion rate, suggesting that receptor energization was necessary for ligand release. We propose a model to explain the observed Ton-dependent changes in the binding parameters and exposures of TbpA and TbpB.
Authors:
C N Cornelissen; J E Anderson; P F Sparling
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Molecular microbiology     Volume:  26     ISSN:  0950-382X     ISO Abbreviation:  Mol. Microbiol.     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1998-01-27     Completed Date:  1998-01-27     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8712028     Medline TA:  Mol Microbiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  25-35     Citation Subset:  IM    
Affiliation:
Department of Medicine, School of Medicine, University of North Carolina at Chapel Hill, USA. ccornelissen@gems.vcu.edu
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MeSH Terms
Descriptor/Qualifier:
Bacterial Outer Membrane Proteins / genetics,  metabolism
Bacterial Proteins / genetics,  metabolism*
Blotting, Western
Carrier Proteins / genetics,  metabolism*
Energy Metabolism
Iron / metabolism*
Iron-Binding Proteins
Kinetics
Membrane Proteins / genetics,  metabolism*
Models, Molecular
Mutagenesis, Site-Directed
Neisseria gonorrhoeae / chemistry,  genetics,  metabolism*
Protein Binding
Protein Conformation
Receptors, Transferrin / chemistry,  metabolism*
Transferrin / metabolism
Transferrin-Binding Proteins
Trypsin / metabolism
Grant Support
ID/Acronym/Agency:
AI26837/AI/NIAID NIH HHS; AI31496/AI/NIAID NIH HHS; AI39523/AI/NIAID NIH HHS
Chemical
Reg. No./Substance:
0/Bacterial Outer Membrane Proteins; 0/Bacterial Proteins; 0/Carrier Proteins; 0/Iron-Binding Proteins; 0/Membrane Proteins; 0/Receptors, Transferrin; 0/Transferrin-Binding Proteins; 0/tonB protein, Bacteria; 11096-37-0/Transferrin; 7439-89-6/Iron; EC 3.4.21.4/Trypsin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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