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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
Authors:
Jean L.
Whittingham
(University of York)
,
Juanna
Carrero‑lerida
(Instituto de Parasitología y Biomedicina ‘López-Neyra’)
,
James A.
Brannigan
(University of York)
,
Luis M.
Ruiz-perez
(Instituto de Parasitología y Biomedicina ‘López-Neyra’)
,
Ana P. G.
Silva
(University of Manchester)
,
Mark J.
Fogg
(University of York)
,
Anthony J.
Wilkinson
(University of York)
,
Ian H.
Gilbert
(University of Dundee)
,
Keith S.
Wilson
(University of York)
,
Dolores
González-pacanowska
(Instituto de Parasitología y Biomedicina ‘López-Neyra’)
Co-authored by industrial partner:
No
Type:
Journal Paper
Journal:
Biochemical Journal
, VOL 428 (3)
, PAGES 499509
State:
Published (Approved)
Published:
May 2010
Abstract: 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.
Subject Areas:
Biology and Bio-materials,
Chemistry
Instruments:
I24-Microfocus Macromolecular Crystallography
Added On:
14/07/2010 11:27
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