Publication: Insights into the role of the junctional region of Plasmodium falciparum dihydrofolate reductase-thymidylate synthase
Issued Date
2013
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eng
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Mahidol University
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BioMed Central
Bibliographic Citation
Malaria Journal. Vol. 12, (2013), 91
Suggested Citation
Natpasit Chaianantakul, Rachada Sirawaraporn, Worachart Sirawaraporn Insights into the role of the junctional region of Plasmodium falciparum dihydrofolate reductase-thymidylate synthase. Malaria Journal. Vol. 12, (2013), 91. doi:10.1186/1475-2875-12-91 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/2728
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Title
Insights into the role of the junctional region of Plasmodium falciparum dihydrofolate reductase-thymidylate synthase
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Abstract
Background: Plasmodium falciparum dihydrofolate reductase-thymidylate synthase (pfDHFR-TS) is a well-defined
target of anti-malarial drug, such as pyrimethamine and cycloguanil. Emergence of malaria parasites resistant to
these drugs has been shown to be associated with point mutations of the gene coding for the target enzymes.
Although the 3D-structure of P. falciparum bifunctional pfDHFR-TS has been reported previously, relatively little is
known about the interactions between the pfDHFR and pfTS domains and the roles of the junctional region that
links the two domains together. Therefore, a thorough understanding of the interaction of the two domains and
the role of the junctional region of this target is important as the knowledge could assist the development of new
effective anti-malarial drugs aimed at overcoming drug-resistant malaria.
Methods: A system was developed to investigate the interaction between pfDHFR and pfTS domains and the role
of the junctional region on the activity of the recombinant pfTS. Based on the ability of co-transformed plasmids
coding for pfDHFR and pfTS with truncated junctional region to complement the growth of TS-deficient Escherichia
coli strain χ2913recA(DE3) on minimum media without thymidine supplementation, active pfTS mutants with
minimal length of junctional region were identified. Interactions between active pfDHFR and the pfTS domains
were demonstrated by using a bacterial two-hybrid system.
Results: Using TS-deficient E. coli strain χ2913recA(DE3), the authors have shown for the first time that in
P. falciparum a junctional region of at least 44 amino acids or longer was necessary for the pfTS domain to be
active for the synthesis of thymidylate for the cells. Truncation of the junctional region of the bifunctional
pfDHFR-TS further confirmed the above results, and suggested that a critical length of the junctional peptide of
pfDHFR-TS would be essential for the activity of TS to catalyze the synthesis of thymidylate.
Conclusion: The present study demonstrated the interactions between the pfDHFR and pfTS domains of the
bifunctional pfDHFR-TS, and revealed that the junctional region linking the two protein domains is essential for the
expression of catalytically active pfTS domain. The findings could be useful since inhibition of the pfDHFR-TS
domain-domain interaction could form a basis for the development of new anti-malarial drugs based on targeting
the non-active site region of this important enzyme.