Linked Life Data

18092817

Source:http://linkedlifedata.com/resource/pubmed/id/18092817

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2008-1-9
pubmed:abstractText
The sterile alpha motifs or SAM domains are small ( approximately 70 amino acids) protein-protein interaction modules that are involved in diverse functions ranging from cell signaling, transcription regulation, and scaffolding. The Ste11 protein kinase in the mitogen-activated protein kinase (MAPK) signaling cascades of the budding yeast is regulated by a SAM domain located at the N-terminus of the full-length protein. The Ste11 SAM domain forms a symmetrical dimeric structure with an interface stabilized presumably by hydrophobic and ionic interactions. Here, we investigated urea-induced unfolding, using NMR and other optical spectroscopic methods, of the dimeric Ste11 SAM domain and two of the variants, namely, L57R and L60R, each containing a point mutation at the interfacial region. Our results demonstrate that the residue-specific or global unfolding of the Ste11 SAM is highly cooperative without any evidence for folded monomeric or partially folded species. However, replacement of hydrophobic residues with basic residues in the interface caused considerable changes in the stability and folding of the Ste11 SAM domain. The native dimeric structure of the L60R mutant protein is severely affected as indicated by a high propensity toward aggregation. On the other hand, the L57R mutant, although retaining the native structure, shows a dramatic decrease in the conformational stability as revealed by urea-induced denaturation and amide proton exchange studies. Furthermore, isothermal titration calorimetry and intrinsic tryptophan fluorescence experiments demonstrate that the L57R interacts with the cognate SAM domain from Ste50 with reduced affinity, while the L60R protein is devoid of any detectable binding activity. These results demonstrate that the interfacial residues of the dimeric SAM domain of Ste11 are critically involved in its structural stability and binding to the Ste50 SAM domain.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
47
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
651-9
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed-meshheading:18092817-Amino Acids, pubmed-meshheading:18092817-Calorimetry, pubmed-meshheading:18092817-Dimerization, pubmed-meshheading:18092817-Enzyme Stability, pubmed-meshheading:18092817-Fluorescence, pubmed-meshheading:18092817-MAP Kinase Kinase Kinases, pubmed-meshheading:18092817-Models, Molecular, pubmed-meshheading:18092817-Mutant Proteins, pubmed-meshheading:18092817-Mutation, pubmed-meshheading:18092817-Nitrogen Isotopes, pubmed-meshheading:18092817-Protein Conformation, pubmed-meshheading:18092817-Protein Folding, pubmed-meshheading:18092817-Protein Structure, Tertiary, pubmed-meshheading:18092817-Saccharomyces cerevisiae Proteins, pubmed-meshheading:18092817-Saccharomycetales, pubmed-meshheading:18092817-Structure-Activity Relationship, pubmed-meshheading:18092817-Titrimetry
pubmed:year
2008
pubmed:articleTitle
Equilibrium unfolding of the dimeric SAM domain of MAPKKK Ste11 from the budding yeast: role of the interfacial residues in structural stability and binding.
pubmed:affiliation
Biomolecular NMR and Drug Discovery Laboratory, Division of Structural and Computational Biology, School of Biological Sciences, Nanyang Technological University, Singapore 637551.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't