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  • The EMBO Journal (2005) 24, 2294 - 2305
  • doi:10.1038/sj.emboj.7600681

Published online: 9 June 2005

A critical role for PfCRT K76T in Plasmodium falciparum verapamil-reversible chloroquine resistance

Viswanathan Lakshmanan1, Patrick G Bray2, Dominik Verdier-Pinard1, David J Johnson1, Paul Horrocks3, Rebecca A Muhle1, George E Alakpa1, Ruth H Hughes2, Steve A Ward2, Donald J Krogstad4, Amar Bir Singh Sidhu1 and David A Fidock1

  1. Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
  2. Molecular and Biochemical Parasitology Group, Liverpool School of Tropical Medicine, Liverpool, UK
  3. Weatherall Institute of Molecular Medicine, University of Oxford, UK
  4. Department of Tropical Medicine, Tulane School of Public Health, New Orleans, LA, USA

Correspondence to:

Patrick G Bray, Molecular and Biochemical Parasitology Group, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK. Tel.: +44 151 705 3119; Fax: +44 151 708 9007; E-mail: p.g.bray@liv.ac.uk

David A Fidock, Department of Microbiology and Immunology, Albert Einstein College of Medicine, Forchheimer 403, 1300 Morris Park Avenue, Bronx, NY 10461, USA. Tel.: +1 718 430 3759; Fax: +1 718 430 8711; E-mail: dfidock@aecom.yu.edu

Received 15 December 2004; Accepted 26 April 2005

Chloroquine resistance (CQR) in Plasmodium falciparum is associated with mutations in the digestive vacuole transmembrane protein PfCRT. However, the contribution of individual pfcrt mutations has not been clarified and other genes have been postulated to play a substantial role. Using allelic exchange, we show that removal of the single PfCRT amino-acid change K76T from resistant strains leads to wild-type levels of CQ susceptibility, increased binding of CQ to its target ferriprotoporphyrin IX in the digestive vacuole and loss of verapamil reversibility of CQ and quinine resistance. Our data also indicate that PfCRT mutations preceding residue 76 modulate the degree of verapamil reversibility in CQ-resistant lines. The K76T mutation accounts for earlier observations that CQR can be overcome by subtly altering the CQ side-chain length. Together, these findings establish PfCRT K76T as a critical component of CQR and suggest that CQ access to ferriprotoporphyrin IX is determined by drug–protein interactions involving this mutant residue.

  • Keywords:

    • chloroquine resistance,
    • drug accumulation,
    • ferriprotoporphyrin IX,
    • pfcrt,
    • verapamil