1xsx
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(New page: 200px<br /><applet load="1xsx" size="450" color="white" frame="true" align="right" spinBox="true" caption="1xsx" /> '''NMR Structure of Sso10a, a Hyperthermophile ...)
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Revision as of 00:43, 25 November 2007
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NMR Structure of Sso10a, a Hyperthermophile DNA-binding Protein with an Extended Anti-parallel Coiled Coil
Overview
Sso10a is one of a number of DNA-binding proteins from the, hyperthermophile Sulfolobus solfataricus that has been associated with DNA, packaging and chromatin regulation. Sequence analysis indicates that it is, a member of a conserved group of archaeal transcription regulators, (COG3432). We have determined the solution structure of Sso10a and show, that it is a homodimer of winged-helix DNA-binding domains. The dimer, interface consists of an extended antiparallel coiled coil, with the, globular DNA-binding domains positioned at opposite ends of a, solvent-exposed coiled-coil rod. NMR structure refinement of the elongated, structure benefited not only from the inclusion of residual dipolar, couplings from partially aligned samples but also the influence of, anisotropic rotational diffusion on heteronuclear relaxation. An analysis, of backbone mobility using (15)N relaxation rates indicated that the, overall tertiary and quaternary structure is largely inflexible on the, nanosecond to picosecond time scale. Amide hydrogen exchange data, demonstrated that the most stable region of the protein extends from the, core of the winged helices into the coiled coil. The positions of the, globular heads relative to the coiled coil in solution deviate only, slightly from that observed in a crystal structure. The most significant, difference between the solution and crystal structures occurs in the, putative DNA-binding helix-turn-helix (HTH) motif. This is the region of, lowest stability in solution and a point of protein-protein contact in the, crystal. Alternative conformations of the HTH motif may permit adjustment, of the structure for optimal DNA binding.
About this Structure
1XSX is a Protein complex structure of sequences from Sulfolobus solfataricus. Full crystallographic information is available from OCA.
Reference
Solution structure, stability, and flexibility of Sso10a: a hyperthermophile coiled-coil DNA-binding protein., Kahsai MA, Vogler B, Clark AT, Edmondson SP, Shriver JW, Biochemistry. 2005 Mar 1;44(8):2822-32. PMID:15723526
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