Gene encoding a deubiquitinating enzyme is mutated in artesunate- and chloroquine-resistant rodent malaria parasites.
Artemisinin- and artesunate-resistant Plasmodium chabaudi mutants, AS-ART and AS-ATN, were previously selected from chloroquine-resistant clones AS-30CQ and AS-15CQ respectively. Now, a genetic cross between AS-ART and the artemisinin-sensitive clone AJ has been analysed by Linkage Group Selection. A genetic linkage group on chromosome 2 was selected under artemisinin treatment. Within this locus, we identified two different mutations in a gene encoding a deubiquitinating enzyme. A distinct mutation occurred in each of the clones AS-30CQ and AS-ATN, relative to their respective progenitors in the AS lineage. The mutations occurred independently in different clones under drug selection with chloroquine (high concentration) or artesunate. Each mutation maps to a critical residue in a homologous human deubiquitinating protein structure. Although one mutation could theoretically account for the resistance of AS-ATN to artemisinin derivates, the other cannot account solely for the resistance of AS-ART, relative to the responses of its sensitive progenitor AS-30CQ. Two lines of Plasmodium falciparum with decreased susceptibility to artemisinin were also selected. Their drug-response phenotype was not genetically stable. No mutations in the UBP-1 gene encoding the P. falciparum orthologue of the deubiquitinating enzyme were observed. The possible significance of these mutations in parasite responses to chloroquine or artemisinin is discussed.
Hunt
Paul
P
Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Ashworth Laboratory, Kings Buildings, Edinburgh EH9 3JT, UK. Paul.Hunt@ed.ac.uk
Afonso
Ana
A
Creasey
Alison
A
Culleton
Richard
R
Sidhu
Amar Bir Singh
AB
Logan
John
J
Valderramos
Stephanie G
SG
McNae
Iain
I
Cheesman
Sandra
S
do Rosario
Virgilio
V
Carter
Richard
R
Fidock
David A
DA
Cravo
Pedro
P
D000595:Amino Acid Sequence; D000818:Animals; D000962:Antimalarials / Q000494:pharmacology; D037621:Artemisinins / Q000494:pharmacology; D000077332:Artesunate; D002738:Chloroquine / Q000494:pharmacology; D004351:Drug Resistance / Q000235:genetics*; D005260:Female; D017125:Genes, Protozoan; D006801:Humans; D051379:Mice; D008808:Mice, Inbred CBA; D008958:Models, Molecular; D009154:Mutation; D021261:Parasitic Sensitivity Tests; D016788:Plasmodium chabaudi / Q000187:drug effects* / Q000201:enzymology* / Q000235:genetics; D012717:Sesquiterpenes / Q000494:pharmacology; D025801:Ubiquitin / Q000378:metabolism*
D000962:Antimalarials; D037621:Artemisinins; D012717:Sesquiterpenes; D025801:Ubiquitin; D000077332:Artesunate; D002738:Chloroquine; C031327:artemisinin