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Artemisinin resistance in rodent malaria - mutation in the AP2 adaptor μ-chain suggests involvement of endocytosis and membrane protein trafficking

Gisela Henriques19*, Axel Martinelli1102, Louise Rodrigues1, Katarzyna Modrzynska102, Richard Fawcett2, Douglas R Houston3, Sofia T Borges1, Umberto d’Alessandro4, Halidou Tinto5, Corine Karema6, Paul Hunt27 and Pedro Cravo18

Author Affiliations

1 Centro de Malaria & Doenças Tropicais.LA/IHMT/Universidade Nova de Lisboa, Lisbon, Portugal

2 Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK

3 Institute for Structural and Molecular Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK

4 Prince Leopold Institute of Tropical Medicine, Antwerp, Belgium

5 Centre Muraz/Institut de Recherche en Sciences de la Santé, Bobo Dioulasso, Burkina Faso

6 National Malaria Control Programme, Kigali, Rwanda

7 Centre of Immunity, Infection and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, UK

8 Instituto de Patologia Tropical e Saúde Pública/Universidade Federal de Goiás, CAPES/Brazil, Goiânia, 74605-050, Brazil

9 Current address: London School of Hygiene and Tropical Medicine, Room 490, Keppel Street, London, WC1E 7HT, UK

10 Current address: Wellcome Trust Sanger Institute, Hinxton, Cambridgshire, UK

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Malaria Journal 2013, 12:118  doi:10.1186/1475-2875-12-118

Published: 5 April 2013

Abstract

Background

The control of malaria, caused by Plasmodium falciparum, is hampered by the relentless evolution of drug resistance. Because artemisinin derivatives are now used in the most effective anti-malarial therapy, resistance to artemisinin would be catastrophic. Indeed, studies suggest that artemisinin resistance has already appeared in natural infections. Understanding the mechanisms of resistance would help to prolong the effective lifetime of these drugs. Genetic markers of resistance are therefore required urgently. Previously, a mutation in a de-ubiquitinating enzyme was shown to confer artemisinin resistance in the rodent malaria parasite Plasmodium chabaudi.

Methods

Here, for a mutant P. chabaudi malaria parasite and its immediate progenitor, the in vivo artemisinin resistance phenotypes and the mutations arising using Illumina whole-genome re-sequencing were compared.

Results

An increased artemisinin resistance phenotype is accompanied by one non-synonymous substitution. The mutated gene encodes the μ-chain of the AP2 adaptor complex, a component of the endocytic machinery. Homology models indicate that the mutated residue interacts with a cargo recognition sequence. In natural infections of the human malaria parasite P. falciparum, 12 polymorphisms (nine SNPs and three indels) were identified in the orthologous gene.

Conclusion

An increased artemisinin-resistant phenotype occurs along with a mutation in a functional element of the AP2 adaptor protein complex. This suggests that endocytosis and trafficking of membrane proteins may be involved, generating new insights into possible mechanisms of resistance. The genotypes of this adaptor protein can be evaluated for its role in artemisinin responses in human infections of P. falciparum.

Keywords:
Malaria; Artemisinin; Drug resistance; Genomics; Plasmodium chabaudi; Mutation; Endocytic machinery