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| - | [[Image:2qg9.jpg|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_2qg9| PDB=2qg9 | SCENE= }} | | {{STRUCTURE_2qg9| PDB=2qg9 | SCENE= }} |
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| - | '''Structure of a regulatory subunit mutant D19A of ATCase from E. coli'''
| + | ===Structure of a regulatory subunit mutant D19A of ATCase from E. coli=== |
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| - | ==Overview==
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| - | Asp19 and His20 of Escherichia coli aspartate transcarbamoylase (EC 2.1.3.2) function in the binding of the triphosphate and ribose moieties of ATP and CTP and thereby may mediate important heterotropic regulation. The roles of these residues were investigated by individually mutating each of them to alanine and determining both the kinetic parameters and the structures of the mutant enzymes. The structures were determined by X-ray crystallography at 2.15 and 2.75 A resolution for His20Ar and Asp19Ar, respectively. Analysis was carried out on the unliganded T-state form. The structures of the mutants did not show gross structural divergence from the canonical T-state, but showed small and systematic differences that were analyzed by global conformational analysis. Structural analysis and comparison with other regulatory-chain mutants confirmed that the Asp19Ar mutant represents the stabilized T-state, while structural analysis of the His20Ar form indicated that it represents an equilibrium shifted towards the R-state. Global analysis of the Asp19Ar and His20Ar enzymes suggested a possible role as molecular modulators of the heterotropic effects caused by the binding of nucleotides at the regulatory site. These studies highlighted the structural determinants of T- or R-state stabilization. Additionally, application of the ;consensus modeling' methodology combined with high-resolution data allowed the determination of unclear structural features contributing to nucleotide specificity and the role of the N-termini of the regulatory chains.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_18084072}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 18084072 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_18084072}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Regulatory chain mutant]] | | [[Category: Regulatory chain mutant]] |
| | [[Category: Transferase/transferase regulator complex]] | | [[Category: Transferase/transferase regulator complex]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 14:54:14 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jul 28 09:38:43 2008'' |
Revision as of 06:38, 28 July 2008
Template:STRUCTURE 2qg9
Structure of a regulatory subunit mutant D19A of ATCase from E. coli
Template:ABSTRACT PUBMED 18084072
About this Structure
2QG9 is a Protein complex structure of sequences from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Comparison of two T-state structures of regulatory-chain mutants of Escherichia coli aspartate transcarbamoylase suggests that His20 and Asp19 modulate the response to heterotropic effectors., Stec B, Williams MK, Stieglitz KA, Kantrowitz ER, Acta Crystallogr D Biol Crystallogr. 2007 Dec;63(Pt 12):1243-53. Epub 2007, Nov 16. PMID:18084072
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