1pm6
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(New page: 200px<br /><applet load="1pm6" size="450" color="white" frame="true" align="right" spinBox="true" caption="1pm6" /> '''Solution Structure of Full-Length Excisionas...)
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Revision as of 21:47, 20 November 2007
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Solution Structure of Full-Length Excisionase (Xis) from Bacteriophage HK022
Overview
Heteronuclear high-resolution NMR spectroscopy was employed to determine, the solution structure of the excisionase protein (Xis) from the, lambda-like bacteriophage HK022 and to study its sequence-specific DNA, interaction. As wild-type Xis was previously characterized as a generally, unstable protein, a biologically active HK022 Xis mutant with a single, amino acid substitution Cys28-->Ser was used in this work. This, substitution has been shown to diminish the irreversibility of Xis, denaturation and subsequent degradation, but does not affect the, structural or thermodynamic properties of the protein, as evidenced by NMR, and differential scanning calorimetry. The solution structure of HK022 Xis, forms a compact, highly ordered protein core with two well-defined, alpha-helices (residues 5-11 and 18-27) and five beta-strands (residues, 2-4, 30-31, 35-36, 41-44 and 48-49). These data correlate well with, 1H2O-2H2O exchange experiments and imply a different organization of the, HK022 Xis secondary structure elements in comparison with the previously, determined structure of the bacteriophage lambda excisionase., Superposition of both Xis structures indicates a better correspondence of, the full-length HK022 Xis to the typical 'winged-helix' DNA-binding motif, as found, for example, in the DNA-binding domain of the Mu-phage, repressor. Residues 51-72, which were not resolved in the lambda Xis, do, not show any regular structure in HK022 Xis and thus appear to be, completely disordered in solution. The resonance assignments have shown, however, that an unusual connectivity exists between residues Asn66 and, Gly67 owing to asparagine-isoaspartyl isomerization. Such an isomerization, has been previously observed and characterized only in eukaryotic, proteins.
About this Structure
1PM6 is a Single protein structure of sequence from Enterobacteria phage hk022. Full crystallographic information is available from OCA.
Reference
Solution structure and stability of the full-length excisionase from bacteriophage HK022., Rogov VV, Lucke C, Muresanu L, Wienk H, Kleinhaus I, Werner K, Lohr F, Pristovsek P, Ruterjans H, Eur J Biochem. 2003 Dec;270(24):4846-58. PMID:14653811
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