Document Detail


Structural allostery and binding of the transferrin*receptor complex.
MedLine Citation:
PMID:  16332734     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The structural allostery and binding interface for the human serum transferrin (Tf)*transferrin receptor (TfR) complex were identified using radiolytic footprinting and mass spectrometry. We have determined previously that the transferrin C-lobe binds to the receptor helical domain. In this study we examined the binding interactions of full-length transferrin with receptor and compared these data with a model of the complex derived from cryoelectron microscopy (cryo-EM) reconstructions (Cheng, Y., Zak, O., Aisen, P., Harrison, S. C. & Walz, T. (2004) Structure of the human transferrin receptor.transferrin complex. Cell 116, 565-576). The footprinting results provide the following novel conclusions. First, we report characteristic oxidations of acidic residues in the C-lobe of native Tf and basic residues in the helical domain of TfR that were suppressed as a function of complex formation; this confirms ionic interactions between these protein segments as predicted by cryo-EM data and demonstrates a novel method for detecting ion pair interactions in the formation of macromolecular complexes. Second, the specific side-chain interactions between the C-lobe and N-lobe of transferrin and the corresponding interactions sites on the transferrin receptor predicted from cryo-EM were confirmed in solution. Last, the footprinting data revealed allosteric movements of the iron binding C- and N-lobes of Tf that sequester iron as a function of complex formation; these structural changes promote tighter binding of the metal ion and facilitate efficient ion transport during endocytosis.
Authors:
Guozhong Xu; Rutao Liu; Olga Zak; Philip Aisen; Mark R Chance
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2005-09-16
Journal Detail:
Title:  Molecular & cellular proteomics : MCP     Volume:  4     ISSN:  1535-9476     ISO Abbreviation:  Mol. Cell Proteomics     Publication Date:  2005 Dec 
Date Detail:
Created Date:  2005-12-07     Completed Date:  2006-03-28     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  101125647     Medline TA:  Mol Cell Proteomics     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1959-67     Citation Subset:  IM    
Affiliation:
Case Center for Proteomics and Mass Spectrometry, Case Western Reserve University, Cleveland, Ohio 44106, USA.
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MeSH Terms
Descriptor/Qualifier:
Allosteric Regulation
Amino Acid Sequence
Binding Sites
Cryoelectron Microscopy
Humans
Iron / metabolism
Mass Spectrometry
Models, Molecular
Molecular Sequence Data
Protein Conformation
Receptors, Transferrin / chemistry*,  metabolism*,  ultrastructure
Grant Support
ID/Acronym/Agency:
P41-EB-01979/EB/NIBIB NIH HHS; R21-DK-69952/DK/NIDDK NIH HHS
Chemical
Reg. No./Substance:
0/Receptors, Transferrin; 7439-89-6/Iron

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