Document Detail


Revealing conformational substates of lipidated N-Ras protein by pressure modulation.
MedLine Citation:
PMID:  22203965     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Regulation of protein function is often linked to a conformational switch triggered by chemical or physical signals. To evaluate such conformational changes and to elucidate the underlying molecular mechanisms of subsequent protein function, experimental identification of conformational substates and characterization of conformational equilibria are mandatory. We apply pressure modulation in combination with FTIR spectroscopy to reveal equilibria between spectroscopically resolved substates of the lipidated signaling protein N-Ras. Pressure has the advantage that its thermodynamic conjugate is volume, a parameter that is directly related to structure. The conformational dynamics of N-Ras in its different nucleotide binding states in the absence and presence of a model biomembrane was probed by pressure perturbation. We show that not only nucleotide binding but also the presence of the membrane has a drastic effect on the conformational dynamics and selection of conformational substates of the protein, and a new substate appearing upon membrane binding could be uncovered. Population of this new substate is accompanied by structural reorientations of the G domain, as also indicated by complementary ATR-FTIR and IRRAS measurements. These findings thus illustrate that the membrane controls signaling conformations by acting as an effective interaction partner, which has consequences for the G-domain orientation of membrane-associated N-Ras, which in turn is known to be critical for its effector and modulator interactions. Finally, these results provide insights into the influence of pressure on Ras-controlled signaling events in organisms living under extreme environmental conditions as they are encountered in the deep sea where pressures reach the kbar range.
Authors:
Shobhna Kapoor; Gemma Triola; Ingrid R Vetter; Mirko Erlkamp; Herbert Waldmann; Roland Winter
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2011-12-27
Journal Detail:
Title:  Proceedings of the National Academy of Sciences of the United States of America     Volume:  109     ISSN:  1091-6490     ISO Abbreviation:  Proc. Natl. Acad. Sci. U.S.A.     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-01-11     Completed Date:  2012-03-12     Revised Date:  2013-06-26    
Medline Journal Info:
Nlm Unique ID:  7505876     Medline TA:  Proc Natl Acad Sci U S A     Country:  United States    
Other Details:
Languages:  eng     Pagination:  460-5     Citation Subset:  IM    
Affiliation:
Physical Chemistry I-Biophysical Chemistry, Faculty of Chemistry, TU Dortmund University, Otto-Hahn-Strasse 6, D-44227 Dortmund, Germany.
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MeSH Terms
Descriptor/Qualifier:
Lipids / chemistry
Membranes / metabolism*
Models, Molecular*
Pressure*
Protein Conformation*
Signal Transduction / genetics*
Spectroscopy, Fourier Transform Infrared
ras Proteins / chemistry*,  metabolism
Chemical
Reg. No./Substance:
0/Lipids; EC 3.6.5.2/ras Proteins
Comments/Corrections

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