The Magnitude of the Allosteric Conformational Transition of Aspartate Transcarbamylase Is Altered by Mutations

Global conformational transitions are of central functional importance for many enzymes and binding proteins. It is not known, however, how much variability can exist in such structural−functional linkages. We have characterized the global magnitude of the T to R conformational transition of Escheri...

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Bibliographic Details
Published in:Biochemistry (Easton) 1998-12, Vol.37 (50), p.17381-17385
Main Authors: LiCata, Vince J, Burz, David S, Moerke, Nathan J, Allewell, Norma M
Format: Article
Language:English
Subjects:
Allosteric Regulation - genetics
Allosteric Site - genetics
Aspartate Carbamoyltransferase - chemistry
Aspartate Carbamoyltransferase - genetics
Aspartate Carbamoyltransferase - metabolism
Catalysis
Enzyme Activation - genetics
Escherichia coli
Models, Molecular
Mutagenesis, Site-Directed
Osmotic Pressure
Protein Conformation
Structure-Activity Relationship
Thermodynamics
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Summary:Global conformational transitions are of central functional importance for many enzymes and binding proteins. It is not known, however, how much variability can exist in such structural−functional linkages. We have characterized the global magnitude of the T to R conformational transition of Escherichia coli aspartate transcarbamylase (ATCase) by measuring (1) hydration changes using osmotic stress and (2) hydrodynamic changes using high-precision analytical gel chromatography. We find that specific mutations can alter the structural magnitude of the enzyme's conformational transition without abolishing allostery, suggesting that some degree of plasticity exists in the conformational component of allostery.
ISSN:0006-2960
1520-4995
DOI:10.1021/bi981073m