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  • 1
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    Dynamic activation of an allosteric regulatory protein (2009)
    Nature Publishing Group (NPG)
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    Publication Date: 2009-11-20
    Description: Allosteric regulation is used as a very efficient mechanism to control protein activity in most biological processes, including signal transduction, metabolism, catalysis and gene regulation. Allosteric proteins can exist in several conformational states with distinct binding or enzymatic activity. Effectors are considered to function in a purely structural manner by selectively stabilizing a specific conformational state, thereby regulating protein activity. Here we show that allosteric proteins can be regulated predominantly by changes in their structural dynamics. We have used NMR spectroscopy and isothermal titration calorimetry to characterize cyclic AMP (cAMP) binding to the catabolite activator protein (CAP), a transcriptional activator that has been a prototype for understanding effector-mediated allosteric control of protein activity. cAMP switches CAP from the 'off' state (inactive), which binds DNA weakly and non-specifically, to the 'on' state (active), which binds DNA strongly and specifically. In contrast, cAMP binding to a single CAP mutant, CAP-S62F, fails to elicit the active conformation; yet, cAMP binding to CAP-S62F strongly activates the protein for DNA binding. NMR and thermodynamic analyses show that despite the fact that CAP-S62F-cAMP(2) adopts the inactive conformation, its strong binding to DNA is driven by a large conformational entropy originating in enhanced protein motions induced by DNA binding. The results provide strong evidence that changes in protein motions may activate allosteric proteins that are otherwise structurally inactive.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tzeng, Shiou-Ru -- Kalodimos, Charalampos G -- England -- Nature. 2009 Nov 19;462(7271):368-72. doi: 10.1038/nature08560.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry & Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19924217" target="_blank"〉PubMed〈/a〉
    Keywords: Cyclic AMP/chemistry/metabolism ; Cyclic AMP Receptor Protein/chemistry/*metabolism ; DNA/metabolism ; *Energy Metabolism ; Escherichia coli/*metabolism ; Escherichia coli Proteins/chemistry/*metabolism ; Models, Molecular ; Protein Binding ; Protein Structure, Tertiary
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 2
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    Protein activity regulation by conformational entropy (2012)
    Nature Publishing Group (NPG)
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    Publication Date: 2012-07-18
    Description: How the interplay between protein structure and internal dynamics regulates protein function is poorly understood. Often, ligand binding, post-translational modifications and mutations modify protein activity in a manner that is not possible to rationalize solely on the basis of structural data. It is likely that changes in the internal motions of proteins have a major role in regulating protein activity, but the nature of their contributions remains elusive, especially in quantitative terms. Here we show that changes in conformational entropy can determine whether protein-ligand interactions will occur, even among protein complexes with identical binding interfaces. We have used NMR spectroscopy to determine the changes in structure and internal dynamics that are elicited by the binding of DNA to several variants of the catabolite activator protein (CAP) that differentially populate the inactive and active DNA-binding domain states. We found that the CAP variants have markedly different affinities for DNA, despite the CAP-DNA-binding interfaces being essentially identical in the various complexes. Combined with thermodynamic data, the results show that conformational entropy changes can inhibit the binding of CAP variants that are structurally poised for optimal DNA binding or can stimulate the binding activity of CAP variants that only transiently populate the DNA-binding-domain active state. Collectively, the data show how changes in fast internal dynamics (conformational entropy) and slow internal dynamics (energetically excited conformational states) can regulate binding activity in a way that cannot be predicted on the basis of the protein's ground-state structure.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Tzeng, Shiou-Ru -- Kalodimos, Charalampos G -- England -- Nature. 2012 Aug 9;488(7410):236-40. doi: 10.1038/nature11271.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Chemistry & Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22801505" target="_blank"〉PubMed〈/a〉
    Keywords: Binding Sites ; Cyclic AMP Receptor Protein/*chemistry/genetics/*metabolism ; DNA/chemistry/metabolism ; *Entropy ; Models, Molecular ; Motion ; Nuclear Magnetic Resonance, Biomolecular ; Protein Binding ; Protein Structure, Tertiary ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Published by Nature Publishing Group (NPG)
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  • 3
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    Structures of ODC-Az and AzIN-Az complexes [Biochemistry] (2015)
    National Academy of Sciences
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    Publication Date: 2015-09-09
    Description: Polyamines are organic polycations essential for cell growth and differentiation; their aberrant accumulation is often associated with diseases, including many types of cancer. To maintain polyamine homeostasis, the catalytic activity and protein abundance of ornithine decarboxylase (ODC), the committed enzyme for polyamine biosynthesis, are reciprocally controlled by the regulatory proteins...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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