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'''STRUCTURE R271L MUTANT OF E. COLI PYRUVATE KINASE''' | '''STRUCTURE R271L MUTANT OF E. COLI PYRUVATE KINASE''' | ||
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[[Category: Fortin, R.]] | [[Category: Fortin, R.]] | ||
[[Category: Mattevi, A.]] | [[Category: Mattevi, A.]] | ||
[[Category: | [[Category: Allostery]] | ||
[[Category: | [[Category: Glycolysis]] | ||
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Revision as of 14:31, 2 May 2008
STRUCTURE R271L MUTANT OF E. COLI PYRUVATE KINASE
OverviewOverview
Pyruvate kinase (PK) is critical for the regulation of the glycolytic pathway. The regulatory properties of Escherichia coli were investigated by mutating six charged residues involved in interdomain salt bridges (Arg(271), Arg(292), Asp(297), and Lys(413)) and in the binding of the allosteric activator (Lys(382) and Arg(431)). Arg(271) and Lys(413) are located at the interface between A and C domains within one subunit. The R271L and K413Q mutant enzymes exhibit altered kinetic properties. In K413Q, there is partial enzyme activation, whereas R271L is characterized by a bias toward the T-state in the allosteric equilibrium. In the T-state, Arg(292) and Asp(297) form an intersubunit salt bridge. The mutants R292D and D297R are totally inactive. The crystal structure of R292D reveals that the mutant enzyme retains the T-state quaternary structure. However, the mutation induces a reorganization of the interface with the creation of a network of interactions similar to that observed in the crystal structures of R-state yeast and M1 PK proteins. Furthermore, in the R292D structure, two loops that are part of the active site are disordered. The K382Q and R431E mutations were designed to probe the binding site for fructose 1, 6-bisphosphate, the allosteric activator. R431E exhibits only slight changes in the regulatory properties. Conversely, K382Q displays a highly altered responsiveness to the activator, suggesting that Lys(382) is involved in both activator binding and allosteric transition mechanism. Taken together, these results support the notion that domain interfaces are critical for the allosteric transition. They couple changes in the tertiary and quaternary structures to alterations in the geometry of the fructose 1, 6-bisphosphate and substrate binding sites. These site-directed mutagenesis data are discussed in the light of the molecular basis for the hereditary nonspherocytic hemolytic anemia, which is caused by mutations in human erythrocyte PK gene.
About this StructureAbout this Structure
1E0U is a Single protein structure of sequence from Escherichia coli. The following page contains interesting information on the relation of 1E0U with [The Glycolytic Enzymes]. Full crystallographic information is available from OCA.
ReferenceReference
The allosteric regulation of pyruvate kinase., Valentini G, Chiarelli L, Fortin R, Speranza ML, Galizzi A, Mattevi A, J Biol Chem. 2000 Jun 16;275(24):18145-52. PMID:10751408 Page seeded by OCA on Fri May 2 14:31:13 2008