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Conformational ensemble modulates cooperativity in the rate-determining catalytic step in the E1 component of the Escherichia coli pyruvate dehydrogenase multienzyme complex.
- Source :
-
The Journal of biological chemistry [J Biol Chem] 2009 Nov 27; Vol. 284 (48), pp. 33122-9. Date of Electronic Publication: 2009 Sep 29. - Publication Year :
- 2009
-
Abstract
- Cooperativity is extensively used by enzymes, particularly those acting at key metabolic branch points, to "fine tune" catalysis. Thus, cooperativity and enzyme catalysis are intimately linked, yet their linkage is poorly understood. Here we show that negative cooperativity in the rate-determining step in the E1 component of the Escherichia coli pyruvate dehydrogenase multienzyme complex is an outcome of redistribution of a "rate-promoting" conformational pre-equilibrium. An array of biophysical and biochemical studies indicates that non-catalytic but conserved residues directly regulate the redistribution. Furthermore, factors such as ligands and temperature, individually or in concert, also strongly influence the redistribution. As a consequence, these factors also exert their influence on catalysis by profoundly influencing the pre-equilibrium facilitated dynamics of communication between multienzyme components. Our observations suggest a mode of cooperativity in the E1 component that is consistent with the dynamical hypothesis shown to satisfactorily explain cooperativity in many well studied enzymes. The results point to the likely existence of multiple modes of communication between subunits when the entire class of thiamin diphosphate-dependent enzymes is considered.
- Subjects :
- Binding Sites genetics
Catalysis
Catalytic Domain genetics
Circular Dichroism
Escherichia coli genetics
Escherichia coli Proteins genetics
Escherichia coli Proteins metabolism
Kinetics
Magnetic Resonance Spectroscopy
Mutation
Protein Binding
Protein Structure, Tertiary
Pyruvate Dehydrogenase Complex genetics
Pyruvate Dehydrogenase Complex metabolism
Thermodynamics
Escherichia coli enzymology
Escherichia coli Proteins chemistry
Protein Conformation
Pyruvate Dehydrogenase Complex chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1083-351X
- Volume :
- 284
- Issue :
- 48
- Database :
- MEDLINE
- Journal :
- The Journal of biological chemistry
- Publication Type :
- Academic Journal
- Accession number :
- 19801660
- Full Text :
- https://doi.org/10.1074/jbc.M109.065508