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PDBsum entry 2wwh
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References listed in PDB file
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Key reference
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Title
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Structural basis for the efficient phosphorylation of azt-Mp (3'-Azido-3'-Deoxythymidine monophosphate) and dgmp by plasmodium falciparum type i thymidylate kinase.
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Authors
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J.L.Whittingham,
J.Carrero-Lerida,
J.A.Brannigan,
L.M.Ruiz-Perez,
A.P.Silva,
M.J.Fogg,
A.J.Wilkinson,
I.H.Gilbert,
K.S.Wilson,
D.González-Pacanowska.
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Ref.
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Biochem J, 2010,
428,
499-509.
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PubMed id
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Abstract
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Plasmodium falciparum is the causative agent of malaria, a disease where new
drug targets are required due to increasing resistance to current
anti-malarials. TMPK (thymidylate kinase) is a good candidate as it is essential
for the synthesis of dTTP, a critical precursor of DNA and has been much studied
due to its role in prodrug activation and as a drug target. Type I TMPKs, such
as the human enzyme, phosphorylate the substrate AZT
(3'-azido-3'-deoxythymidine)-MP (monophosphate) inefficiently compared with type
II TMPKs (e.g. Escherichia coli TMPK). In the present paper we report that
eukaryotic PfTMPK (P. falciparum TMPK) presents sequence features of a type I
enzyme yet the kinetic parameters for AZT-MP phosphorylation are similar to
those of the highly efficient E. coli enzyme. Structural information shows that
this is explained by a different juxtaposition of the P-loop and the azide of
AZT-MP. Subsequent formation of the transition state requires no further
movement of the PfTMPK P-loop, with no steric conflicts for the azide moiety,
allowing efficient phosphate transfer. Likewise, we present results that confirm
the ability of the enzyme to uniquely accept dGMP as a substrate and shed light
on the basis for its wider substrate specificity. Information resulting from two
ternary complexes (dTMP-ADP and AZT-MP-ADP) and a binary complex with the
transition state analogue AP5dT [P1-(5'-adenosyl)-P5-(5'-thymidyl)
pentaphosphate] all reveal significant differences with the human enzyme,
notably in the lid region and in the P-loop which may be exploited in the
rational design of Plasmodium-specific TMPK inhibitors with therapeutic
potential.
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