Source:http://linkedlifedata.com/resource/pubmed/id/18175310
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| Predicate | Object |
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| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
4
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| pubmed:dateCreated |
2008-6-2
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| pubmed:abstractText |
Calmodulin (CaM) is the primary transducer of calcium fluxes in eukaryotic cells. Its two domains allosterically regulate myriad target proteins through calcium-linked association and conformational change. Many of these proteins have a basic amphipathic alpha-helix (BAA) motif that binds one or both CaM domains. Previously, we demonstrated domain-specific binding of melittin, a model BAA peptide, to Paramecium CaM (PCaM): C-domain mutations altered the interaction with melittin, whereas N-domain mutations had no discernable effect. Here, we report on the use of fluorescence and NMR spectroscopy to measure the domain-specific association of melittin with calcium-saturated ((Ca(2+))(4)-PCaM) or calcium-depleted (apo) PCaM, which has enabled us to determine the free energies of calcium binding to the PCaM-melittin complex, and to estimate interdomain cooperativity. Under apo conditions, melittin associated with each PCaM domain fragment (PCaM(1-80) and PCaM(76-148)), as well as with the C-domain of full-length PCaM (PCaM(1-148)). In the presence of calcium, all of these interactions were again observed, in addition to which an association with the N-domain of (Ca(2+))(4)-PCaM(1-148) occurred. This new association was made possible by the fact that melittin changed the calcium-binding preferences for the domains from sequential (C > N) to concomitant, decreasing the median ligand activity of calcium toward the N-domain 10-fold more than that observed for the C-domain. This selectivity may be explained by a free energy of cooperativity of -3 kcal/mol between the N- and C-domains. This study demonstrates multiple domain-selective differences in the interactions between melittin and PCaM. Our findings support a model that may apply more generally to ion channels that associate with the C-domain of CaM under low (resting) calcium conditions, but rearrange when calcium binding triggers an association of the N- domain with the channel.
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| pubmed:grant | |
| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/Calcium,
http://linkedlifedata.com/resource/pubmed/chemical/Calmodulin,
http://linkedlifedata.com/resource/pubmed/chemical/Melitten,
http://linkedlifedata.com/resource/pubmed/chemical/Recombinant Proteins,
http://linkedlifedata.com/resource/pubmed/chemical/Tryptophan
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| pubmed:status |
MEDLINE
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| pubmed:month |
Jun
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| pubmed:issn |
1097-0134
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| pubmed:author | |
| pubmed:copyrightInfo |
(c) 2008 Wiley-Liss, Inc.
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| pubmed:issnType |
Electronic
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| pubmed:volume |
71
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
1792-812
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| pubmed:dateRevised |
2010-11-18
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| pubmed:meshHeading |
pubmed-meshheading:18175310-Amino Acid Motifs,
pubmed-meshheading:18175310-Amino Acid Sequence,
pubmed-meshheading:18175310-Animals,
pubmed-meshheading:18175310-Binding Sites,
pubmed-meshheading:18175310-Calcium,
pubmed-meshheading:18175310-Calmodulin,
pubmed-meshheading:18175310-Conserved Sequence,
pubmed-meshheading:18175310-Fluorescence Polarization,
pubmed-meshheading:18175310-Hydrophobic and Hydrophilic Interactions,
pubmed-meshheading:18175310-Kinetics,
pubmed-meshheading:18175310-Melitten,
pubmed-meshheading:18175310-Models, Biological,
pubmed-meshheading:18175310-Models, Molecular,
pubmed-meshheading:18175310-Molecular Sequence Data,
pubmed-meshheading:18175310-Nuclear Magnetic Resonance, Biomolecular,
pubmed-meshheading:18175310-Paramecium,
pubmed-meshheading:18175310-Protein Binding,
pubmed-meshheading:18175310-Protein Conformation,
pubmed-meshheading:18175310-Protein Structure, Secondary,
pubmed-meshheading:18175310-Protein Structure, Tertiary,
pubmed-meshheading:18175310-Recombinant Proteins,
pubmed-meshheading:18175310-Sequence Homology, Amino Acid,
pubmed-meshheading:18175310-Spectrometry, Fluorescence,
pubmed-meshheading:18175310-Thermodynamics,
pubmed-meshheading:18175310-Tryptophan
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| pubmed:year |
2008
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| pubmed:articleTitle |
Interdomain cooperativity of calmodulin bound to melittin preferentially increases calcium affinity of sites I and II.
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| pubmed:affiliation |
Department of Biochemistry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242-1109, USA.
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| pubmed:publicationType |
Journal Article,
Research Support, Non-U.S. Gov't,
Research Support, N.I.H., Extramural
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