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PDBsum entry 4xw5
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References listed in PDB file
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Key reference
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Title
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Phosphoryl transfer reaction snapshots in crystals: insights into the mechanism of protein kinase a catalytic subunit.
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Authors
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O.Gerlits,
J.Tian,
A.Das,
P.Langan,
W.T.Heller,
A.Kovalevsky.
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Ref.
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J Biol Chem, 2015,
290,
15538-15548.
[DOI no: ]
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PubMed id
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Abstract
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To study the catalytic mechanism of phosphorylation catalyzed by cAMP-dependent
protein kinase (PKA) a structure of the enzyme-substrate complex representing
the Michaelis complex is of specific interest as it can shed light on the
structure of the transition state. However, all previous crystal structures of
the Michaelis complex mimics of the PKA catalytic subunit (PKAc) were obtained
with either peptide inhibitors or ATP analogs. Here we utilized Ca(2+) ions and
sulfur in place of the nucleophilic oxygen in a 20-residue pseudo-substrate
peptide (CP20) and ATP to produce a close mimic of the Michaelis complex. In the
ternary reactant complex, the thiol group of Cys-21 of the peptide is facing
Asp-166 and the sulfur atom is positioned for an in-line phosphoryl transfer.
Replacement of Ca(2+) cations with Mg(2+) ions resulted in a complex with
trapped products of ATP hydrolysis: phosphate ion and ADP. The present
structural results in combination with the previously reported structures of the
transition state mimic and phosphorylated product complexes complete the
snapshots of the phosphoryl transfer reaction by PKAc, providing us with the
most thorough picture of the catalytic mechanism to date.
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