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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
9
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pubmed:dateCreated |
1988-1-11
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pubmed:abstractText |
Mutation pAR5 replaces residues 145'-153' at the C terminus of the regulatory (r) chains of Escherichia coli ATCase by a new sequence of six residues. The mutated enzyme has been shown to lack substrate cooperativity and inhibition by CTP. Solution X-ray scattering curves demonstrate that, in the absence of ligands, its structure is intermediate between the T form and the R form. In the presence of N-phosphonacetyl-L-aspartate, the mutant is similar to the wild type. An examination of the crystal structure of unligated ATCase reveals that the mutated site is at an interface between r and catalytic (c) chains, which exists only in the T allosteric form. A computer simulation by energy minimization suggests that the pAR5 mutation destabilizes this interface and induces minor changes in the tertiary structure of r chains. The resulting lower stability of the T form explains the loss of substrate cooperativity. The lack of allosteric inhibition may be related to a new electrostatic interaction made in mutant r chains between the C-terminal carboxylate and a lysine residue of the allosteric domain.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-3586030,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-3856843,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-3900420,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-3912513,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-3912514,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-395314,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6377306,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6551452,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6667333,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6713014,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6756403,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6757446,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-6954462,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-875032,
http://linkedlifedata.com/resource/pubmed/commentcorrection/3315652-985660
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
0261-4189
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
6
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2843-7
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
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pubmed:year |
1987
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pubmed:articleTitle |
The pAR5 mutation and the allosteric mechanism of Escherichia coli aspartate carbamoyltransferase.
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pubmed:affiliation |
Laboratoire de Biologie Physicochimique, Université Paris-Sud, Orsay, France.
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pubmed:publicationType |
Journal Article
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