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Distinctive Solution Conformation of Phosphatase Inhibitor CPI-17 Substituted with Aspartate at the Phosphorylation-site Threonine Residue
- Source :
- Journal of Molecular Biology. 326:1539-1547
- Publication Year :
- 2003
- Publisher :
- Elsevier BV, 2003.
-
Abstract
- We present solution NMR structures for wild-type and mutated forms of CPI-17, a phosphoinhibitor for protein phosphatase 1. Phosphorylation of Thr38 of CPI-17 produces a >1000-fold increase in inhibitory potency for myosin phosphatase. We compared the 1H–15N heteronuclear single quantum coherence spectroscopy (HSQC) chemical shifts of wild-type CPI-17, partially phosphorylated CPI-17 and CPI-17 with Thr38 replaced with Asp to introduce a negative charge. There was a switch in the protein conformation due to either Asp substitution or phosphorylation, so we determined the solution NMR structure of the CPI-17 T38D mutant as a model for the active (phospho-) conformation. The structures reveal a molecular switch in conformation that involves the rotation of two of the four helices in the four helix bundle. Despite this conformational switch, there was little increase in the inhibitory potency with T38D. We propose that for this inhibitor, a negative charge at residue 38 is sufficient to trigger an active conformation, but a phosphoryl group is required for full inhibitory potency against protein phosphatase-1.
- Subjects :
- Models, Molecular
Threonine
HNCA experiment
Protein Conformation
Swine
Stereochemistry
Phosphatase
Muscle Proteins
Inhibitory Concentration 50
Myosin-Light-Chain Phosphatase
Structure-Activity Relationship
Protein structure
Structural Biology
Protein Phosphatase 1
Escherichia coli
Phosphoprotein Phosphatases
Animals
Enzyme Inhibitors
Phosphorylation
Nuclear Magnetic Resonance, Biomolecular
Molecular Biology
Helix bundle
Aspartic Acid
Binding Sites
Chemistry
Protein phosphatase 1
Phosphoproteins
Solutions
Amino Acid Substitution
Vascular smooth muscle contraction
Heteronuclear single quantum coherence spectroscopy
Subjects
Details
- ISSN :
- 00222836
- Volume :
- 326
- Database :
- OpenAIRE
- Journal :
- Journal of Molecular Biology
- Accession number :
- edsair.doi.dedup.....7e679c17eec586b123bc4be6af9b3d2c