1xx8
From Proteopedia
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| - | [[Image:1xx8.gif|left|200px]] | ||
| - | + | ==NMR Structure of the W24A Mutant of the Hyperthermophile Sac7d Protein== | |
| - | + | <StructureSection load='1xx8' size='340' side='right'caption='[[1xx8]]' scene=''> | |
| - | + | == Structural highlights == | |
| - | + | <table><tr><td colspan='2'>[[1xx8]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Sulfolobus_acidocaldarius Sulfolobus acidocaldarius]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1XX8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1XX8 FirstGlance]. <br> | |
| - | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr> | |
| - | - | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1xx8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1xx8 OCA], [https://pdbe.org/1xx8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1xx8 RCSB], [https://www.ebi.ac.uk/pdbsum/1xx8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1xx8 ProSAT]</span></td></tr> |
| - | + | </table> | |
| - | + | == Function == | |
| - | ''' | + | [https://www.uniprot.org/uniprot/DN7D_SULAC DN7D_SULAC] Can constrain negative DNA supercoils. May be involved in maintaining the integrity of the genome at high temperature.[UniProtKB:P61990] |
| - | + | <div style="background-color:#fffaf0;"> | |
| - | + | == Publication Abstract from PubMed == | |
| - | == | + | |
Sac7d is a small, chromatin protein from Sulfolobus acidocaldarius which induces a sharp kink in DNA with intercalation of valine and methionine side chains. The crystal structure of the protein-DNA complex indicates that a surface tryptophan (W24) plays a key role in DNA binding by hydrogen bonding to the DNA at the kink site. We show here that substitution of the solvent-exposed tryptophan with alanine (W24A) led to a significant loss in not only DNA binding affinity but also protein stability. The W24A substitution proved to be one of the most destabilizing surface substitutions in Sac7d. A global linkage analysis of the pH and salt dependence of stability indicated that the protein stability surface (DeltaG vs temperature, pH, and salt concentration) was lowered overall by 2 kcal/mol (from 0 to 100 degrees C, pH 0 to 7, and 0 to 0.3 M KCl). The lower free energy of unfolding could not be attributed to significant structural perturbations of surface electrostatic interactions. Residual dipolar coupling of partially aligned protein and the NMR solution structure of W24A confirmed that the surface substitution resulted in no significant change in structure. Stabilization of this hyperthermophile protein and its DNA complex by a surface cluster of hydrophobic residues involving W24 and the two intercalating side chains is discussed. | Sac7d is a small, chromatin protein from Sulfolobus acidocaldarius which induces a sharp kink in DNA with intercalation of valine and methionine side chains. The crystal structure of the protein-DNA complex indicates that a surface tryptophan (W24) plays a key role in DNA binding by hydrogen bonding to the DNA at the kink site. We show here that substitution of the solvent-exposed tryptophan with alanine (W24A) led to a significant loss in not only DNA binding affinity but also protein stability. The W24A substitution proved to be one of the most destabilizing surface substitutions in Sac7d. A global linkage analysis of the pH and salt dependence of stability indicated that the protein stability surface (DeltaG vs temperature, pH, and salt concentration) was lowered overall by 2 kcal/mol (from 0 to 100 degrees C, pH 0 to 7, and 0 to 0.3 M KCl). The lower free energy of unfolding could not be attributed to significant structural perturbations of surface electrostatic interactions. Residual dipolar coupling of partially aligned protein and the NMR solution structure of W24A confirmed that the surface substitution resulted in no significant change in structure. Stabilization of this hyperthermophile protein and its DNA complex by a surface cluster of hydrophobic residues involving W24 and the two intercalating side chains is discussed. | ||
| - | + | Role of a surface tryptophan in defining the structure, stability, and DNA binding of the hyperthermophile protein Sac7d.,Bedell JL, Edmondson SP, Shriver JW Biochemistry. 2005 Jan 25;44(3):915-25. PMID:15654747<ref>PMID:15654747</ref> | |
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| - | + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |
| - | + | </div> | |
| - | [[Category: | + | <div class="pdbe-citations 1xx8" style="background-color:#fffaf0;"></div> |
| + | == References == | ||
| + | <references/> | ||
| + | __TOC__ | ||
| + | </StructureSection> | ||
| + | [[Category: Large Structures]] | ||
[[Category: Sulfolobus acidocaldarius]] | [[Category: Sulfolobus acidocaldarius]] | ||
| - | [[Category: Bedell | + | [[Category: Bedell JL]] |
| - | [[Category: Edmondson | + | [[Category: Edmondson SP]] |
| - | [[Category: Shriver | + | [[Category: Shriver JW]] |
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Current revision
NMR Structure of the W24A Mutant of the Hyperthermophile Sac7d Protein
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