2z1h
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(New page: 200px<br /><applet load="2z1h" size="350" color="white" frame="true" align="right" spinBox="true" caption="2z1h, resolution 2.60Å" /> '''Crystal structure of...)
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Revision as of 10:17, 23 January 2008
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Crystal structure of E.coli RNase HI surface charged mutant(Q4R/T92K/Q105K/Q113R/Q115K/N143K/T145K)
Overview
Using the information from the genome projects, recent comparative studies, of thermostable proteins have revealed a certain trend of amino acid, composition in which polar residues are scarce and charged residues are, rich on the protein surface. To clarify experimentally the effect of the, amino acid composition of surface residues on the thermostability of, Escherichia coli Ribonuclease HI (RNase HI), we constructed six variants, in which five to eleven polar residues were replaced by charged residues, (5C, 7Ca, 7Cb, 9Ca, 9Cb and 11C). The thermal denaturation experiments, indicated that all of the variant proteins are 3.2-10.1 degrees C in T(m), less stable than the wild proteins. The crystal structures of resultant, protein variants 7Ca, 7Cb, 9Ca and 11C closely resemble that of E. coli, RNase HI in their global fold, and several different hydrogen bonding and, ion-pair interactions are formed by the mutations. Comparison of the, crystal structures of these variant proteins with that of E. coli RNase HI, reveals that thermal destabilization is apparently related to, electrostatic repulsion of the charged residues with neighbours. This, result suggests that charged residues of natural thermostable proteins are, strictly posted on the surface with optimal interactions and without, repulsive interactions.
About this Structure
2Z1H is a Single protein structure of sequence from Escherichia coli. Active as Ribonuclease H, with EC number 3.1.26.4 Full crystallographic information is available from OCA.
Reference
Protein Thermostabilization Requires a Fine-tuned Placement of Surface-charged Residues., You DJ, Fukuchi S, Nishikawa K, Koga Y, Takano K, Kanaya S, J Biochem (Tokyo). 2007 Oct;142(4):507-516. Epub 2007 Aug 30. PMID:17761696
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