1sap
From Proteopedia
(New page: 200px<br /><applet load="1sap" size="450" color="white" frame="true" align="right" spinBox="true" caption="1sap" /> '''HYPERTHERMOPHILE PROTEIN, RELAXATION MATRIX ...) |
|||
| Line 1: | Line 1: | ||
| - | [[Image:1sap.gif|left|200px]]<br /><applet load="1sap" size=" | + | [[Image:1sap.gif|left|200px]]<br /><applet load="1sap" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="1sap" /> | caption="1sap" /> | ||
'''HYPERTHERMOPHILE PROTEIN, RELAXATION MATRIX REFINEMENT STRUCTURE'''<br /> | '''HYPERTHERMOPHILE PROTEIN, RELAXATION MATRIX REFINEMENT STRUCTURE'''<br /> | ||
==Overview== | ==Overview== | ||
| - | The Sac7 proteins from the hyperthermophile Sulfolobus acidocaldarius are | + | The Sac7 proteins from the hyperthermophile Sulfolobus acidocaldarius are a heterogeneous mixture of small, thermostable, nonspecific DNA-binding proteins. One of these proteins, Sac7d, has been overexpressed in Escherichia coli to provide a homogeneous preparation for structure, stability, and function studies. We present here essentially complete sequence-specific 1H NMR assignments for Sac7d, a delineation of secondary structural elements, and the high-resolution solution structure obtained from a full relaxation matrix refinement. The final structure provides an excellent fit to the NMR data with an NOE R-factor of 0.27 for backbone NOEs. The structure has a compact globular fold with 82% of the sequence involved in regular secondary structure: an antiparallel two-stranded beta-ribbon with a tight turn, followed by a short 3(10) helix, an antiparallel three-stranded beta-sheet, another short 3(10) helix, and finally four turns of alpha-helix. The amphipathic alpha-helix packs across the hydrophobic face of the three-stranded beta-sheet in an open-faced sandwich arrangement with at least one turn of the helix exposed beyond the sheet. The hydrophobic face of the beta-ribbon packs against a corner of the twisted beta-sheet. The single tryptophan responsible for the 88% fluorescence quenching upon DNA binding is exposed on the surface of the three-stranded beta-sheet. Lysines 5 and 7, whose monomethylation may be associated with enhanced thermostability, are highly solvent exposed along the inner edge of the two-stranded ribbon. The structure of Sac7d differs in many respects from that reported for the homologous native Sso7d [Baumann et al. (1994) Nature Struct. Biol. 1, 808] with a backbone RMSD greater than 3.0 A, largely due to the packing and length of the C-terminal alpha-helix which may be important in Sac7d DNA binding. |
==About this Structure== | ==About this Structure== | ||
| - | 1SAP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sulfolobus_acidocaldarius Sulfolobus acidocaldarius]. Full crystallographic information is available from [http:// | + | 1SAP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Sulfolobus_acidocaldarius Sulfolobus acidocaldarius]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SAP OCA]. |
==Reference== | ==Reference== | ||
| Line 13: | Line 13: | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Sulfolobus acidocaldarius]] | [[Category: Sulfolobus acidocaldarius]] | ||
| - | [[Category: Edmondson, S | + | [[Category: Edmondson, S P.]] |
| - | [[Category: Shriver, J | + | [[Category: Shriver, J W.]] |
[[Category: dna-binding protein]] | [[Category: dna-binding protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:59:34 2008'' |
Revision as of 12:59, 21 February 2008
|
HYPERTHERMOPHILE PROTEIN, RELAXATION MATRIX REFINEMENT STRUCTURE
Overview
The Sac7 proteins from the hyperthermophile Sulfolobus acidocaldarius are a heterogeneous mixture of small, thermostable, nonspecific DNA-binding proteins. One of these proteins, Sac7d, has been overexpressed in Escherichia coli to provide a homogeneous preparation for structure, stability, and function studies. We present here essentially complete sequence-specific 1H NMR assignments for Sac7d, a delineation of secondary structural elements, and the high-resolution solution structure obtained from a full relaxation matrix refinement. The final structure provides an excellent fit to the NMR data with an NOE R-factor of 0.27 for backbone NOEs. The structure has a compact globular fold with 82% of the sequence involved in regular secondary structure: an antiparallel two-stranded beta-ribbon with a tight turn, followed by a short 3(10) helix, an antiparallel three-stranded beta-sheet, another short 3(10) helix, and finally four turns of alpha-helix. The amphipathic alpha-helix packs across the hydrophobic face of the three-stranded beta-sheet in an open-faced sandwich arrangement with at least one turn of the helix exposed beyond the sheet. The hydrophobic face of the beta-ribbon packs against a corner of the twisted beta-sheet. The single tryptophan responsible for the 88% fluorescence quenching upon DNA binding is exposed on the surface of the three-stranded beta-sheet. Lysines 5 and 7, whose monomethylation may be associated with enhanced thermostability, are highly solvent exposed along the inner edge of the two-stranded ribbon. The structure of Sac7d differs in many respects from that reported for the homologous native Sso7d [Baumann et al. (1994) Nature Struct. Biol. 1, 808] with a backbone RMSD greater than 3.0 A, largely due to the packing and length of the C-terminal alpha-helix which may be important in Sac7d DNA binding.
About this Structure
1SAP is a Single protein structure of sequence from Sulfolobus acidocaldarius. Full crystallographic information is available from OCA.
Reference
Solution structure of the DNA-binding protein Sac7d from the hyperthermophile Sulfolobus acidocaldarius., Edmondson SP, Qiu L, Shriver JW, Biochemistry. 1995 Oct 17;34(41):13289-304. PMID:7577913
Page seeded by OCA on Thu Feb 21 14:59:34 2008
