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Model peptides based on the binding loop of the copper metallochaperone Atx1: selectivity of the consensus sequence MxCxxC for metal ions Hg(II), Cu(I), Cd(II), Pb(II), and Zn(II).
MedLine Citation:
PMID:  16813414     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The amino acid sequence MxCxxC is conserved in many soft-metal transporters that are involved in the control of the intracellular concentration of ions such as Cu(I), Hg(II), Zn(II), Cd(II), and Pb(II). A relevant task is thus the selectivity of the motif MxCxxC for these different metal ions. To analyze the coordination properties and the selectivity of this consensus sequence, we have designed two model peptides that mimic the binding loop of the copper chaperone Atx1: the cyclic peptide P(C) c(GMTCSGCSRP) and its linear analogue P(L) (Ac-MTCSGCSRPG-NH2). By using complementary analytical and spectroscopic methods, we have demonstrated that 1:1 complexes are obtained with Cu(I) and Hg(II), whereas 1:1 and 1:2 (M:P) species are successively formed with Zn(II), Cd(II), and Pb(II). The complexation properties of the cyclic and linear peptides are very close, but the cyclic compound provides systematically higher affinity constants than its unstructured analogue. The introduction of a xPGx motif that forms a type II beta turn in P(C) induces a preorganization of the binding loop of the peptide that enhances the stabilities of the complexes (up to 2 orders of magnitude difference for the Hg complexes). The affinity constants were measured in the absence of any reducing agent that would compete with the peptides and range in the order Hg(II) > Cu(I) >> Cd(II) > Pb(II) > Zn(II). This sequence is thus highly selective for Cu(I) compared to the essential ion Zn(II) that could compete in vivo or compared to the toxic ions Cd(II) and Pb(II). Only Hg(II) may be an efficient competitor of Cu(I) for binding to the MxCxxC motif in metalloproteins.
Authors:
Pierre Rousselot-Pailley; Olivier Sénèque; Colette Lebrun; Serge Crouzy; Didier Boturyn; Pascal Dumy; Michel Ferrand; Pascale Delangle
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Inorganic chemistry     Volume:  45     ISSN:  0020-1669     ISO Abbreviation:  Inorg Chem     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-03     Completed Date:  2007-03-29     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0366543     Medline TA:  Inorg Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  5510-20     Citation Subset:  IM    
Affiliation:
Laboratoire de Reconnaissance Ionique, DRFMC/LCIB (UMR_E 3 CEA-UJF), CEA-Grenoble, 17 rue des Martyrs, F-38054 Grenoble Cedex 9, France.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Motifs
Carrier Proteins / chemistry*
Chromatography, Gel
Conserved Sequence
Metalloproteins / chemical synthesis,  chemistry*
Metals, Heavy / chemistry*
Models, Molecular
Nuclear Magnetic Resonance, Biomolecular
Peptides, Cyclic / chemical synthesis,  chemistry*
Saccharomyces cerevisiae Proteins / chemistry*
Spectrometry, Mass, Electrospray Ionization
Spectrophotometry, Ultraviolet
Chemical
Reg. No./Substance:
0/ATX1 protein, S cerevisiae; 0/Carrier Proteins; 0/Metalloproteins; 0/Metals, Heavy; 0/Peptides, Cyclic; 0/Saccharomyces cerevisiae Proteins

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