Differentiating a Ligand's Chemical Requirements for Allosteric Interactions from Those for Protein Binding. Phenylalanine Inhibition of Pyruvate Kinase
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- 作者：Rachel Williams ; Todd Holyoak ; Gissel McDonald ; Chunshan Gui ; and Aron W. Fenton
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：May 2, 2006
- 年：2006
- 卷：45
- 期：17
- 页码：5421 - 5429
- 全文大小：272K
- 年卷期：v.45,no.17(May 2, 2006)
- ISSN：1520-4995
文摘
The isoform of pyruvate kinase from brain and muscle of mammals (M1-PYK) is allostericallyinhibited by phenylalanine. Initial observations in this model allosteric system indicate that Ala bindscompetitively with Phe, but elicits a minimal allosteric response. Thus, the allosteric ligand of this systemmust have requirements for eliciting an allosteric response in addition to the requirements for binding.Phe analogues have been used to dissect what chemical properties of Phe are responsible for eliciting theallosteric response. We first demonstrate that the L-2-aminopropanaldehyde substructure of the aminoacid ligand is primarily responsible for binding to M1-PYK. Since the allosteric response to Ala is minimaland linear addition of methyl groups beyond the 
-carbon increase the magnitude of the allosteric response,we conclude that moieties beyond the -carbon are primarily responsible for allostery. Instead of an all-or-none mechanism of allostery, these findings support the idea that the bulk of the hydrophobic sidechain, but not the aromatic nature, is the primary determinant of the magnitude of the observed allostericinhibition. The use of these results to direct structural studies has resulted in a 1.65 Å structure of M1-PYK with Ala bound. The coordination of Ala in the allosteric amino acid binding site confirms thebinding role of the L-2-aminopropanaldehyde substructure of the ligand. Collectively, this study confirmsthat a ligand can have chemical regions specific for eliciting the allosteric signal in addition to the chemicalregions necessary for binding.
-carbon increase the magnitude of the allosteric response,we conclude that moieties beyond the -carbon are primarily responsible for allostery. Instead of an all-or-none mechanism of allostery, these findings support the idea that the bulk of the hydrophobic sidechain, but not the aromatic nature, is the primary determinant of the magnitude of the observed allostericinhibition. The use of these results to direct structural studies has resulted in a 1.65 Å structure of M1-PYK with Ala bound. The coordination of Ala in the allosteric amino acid binding site confirms thebinding role of the L-2-aminopropanaldehyde substructure of the ligand. Collectively, this study confirmsthat a ligand can have chemical regions specific for eliciting the allosteric signal in addition to the chemicalregions necessary for binding.