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PDBsum entry 3geq
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References listed in PDB file
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Key reference
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Title
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Comparative analysis of mutant tyrosine kinase chemical rescue.
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Authors
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K.E.Muratore,
M.A.Seeliger,
Z.Wang,
D.Fomina,
J.Neiswinger,
J.J.Havranek,
D.Baker,
J.Kuriyan,
P.A.Cole.
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Ref.
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Biochemistry, 2009,
48,
3378-3386.
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PubMed id
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Abstract
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Protein tyrosine kinases are critical cell signaling enzymes. These enzymes have
a highly conserved Arg residue in their catalytic loop which is present two
residues or four residues downstream from an absolutely conserved Asp catalytic
base. Prior studies on protein tyrosine kinases Csk and Src revealed the
potential for chemical rescue of catalytically deficient mutant kinases (Arg to
Ala mutations) by small diamino compounds, particularly imidazole; however, the
potency and efficiency of rescue was greater for Src. This current study further
examines the structural and kinetic basis of rescue for mutant Src as compared
to mutant Abl tyrosine kinase. An X-ray crystal structure of R388A Src revealed
the surprising finding that a histidine residue of the N-terminus of a
symmetry-related kinase inserts into the active site of the adjacent Src and
mimics the hydrogen-bonding pattern seen in wild-type protein tyrosine kinases.
Abl R367A shows potent and efficient rescue more comparable to Src, even though
its catalytic loop is more like that of Csk. Various enzyme redesigns of the
active sites indicate that the degree and specificity of rescue are somewhat
flexible, but the overall properties of the enzymes and rescue agents play an
overarching role. The newly discovered rescue agent 2-aminoimidazole is about as
efficient as imidazole in rescuing R/A Src and Abl. Rate vs pH studies with
these imidazole analogues suggest that the protonated imidazolium is the
preferred form for chemical rescue, consistent with structural models. The
efficient rescue seen with mutant Abl points to the potential of this approach
to be used effectively to analyze Abl phosphorylation pathways in cells.
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