TY - JOUR
T1 - The role of DNA mismatch repair in generating genetic diversity and drug resistance in malaria parasites
AU - Bethke, Lara
AU - Thomas, Susan
AU - Walker, Kerone
AU - Lakhia, Ronak
AU - Rangarajan, Radha
AU - Wirth, Dyann
N1 - Funding Information:
We thank Timothy Lepore for maintaining mosquito colonies and for assisting with passage of mutant and wild type parasite populations in A. stephensi mosquitoes. We thank Amy Bei, Julia Fisher, and Dr. Kerri Mello for assistance with rodent handling. We would also like to thank Dr. Leona Samson, Dr. Mark Ambrose and Dr. Brian Glassner for their help with setting up the dominant mutator assays. This worked was supported by the NIH (R01-AI050689-03) (AS) and R01-GM061351 (DW).
PY - 2007/9
Y1 - 2007/9
N2 - Although the mechanisms by which malaria parasites develop resistance to drugs are unclear, current knowledge suggests a main mechanism of resistance is the alteration of target enzymes by point mutation. In other organisms, defects in DNA mismatch repair have been linked to increased mutation rates and drug resistance. We have identified an unusual complement of mismatch repair genes in the Plasmodium genome. An initial functional test of two of these genes (PfMSH2-1 and PfMSH2-2) using a dominant mutator assay showed an elevation in mutation frequency with the PfMSH2-2 homolog, indirectly demonstrating a role for this gene in mismatch repair. We successfully disrupted PbMSH2-2 in the Plasmodium berghei laboratory isolate NK65, and showed that this gene is not essential for parasite growth in either the asexual (rodent) or sexual (mosquito) stages of the lifecycle. Although we observed some differences in levels of drug resistance between wild type and mutant parasites, no uniform trend emerged and preliminary evidence does not support a strong link between PbMSH2-2 disruption and dramatically increased drug resistance. We found microsatellite polymorphism in the PbMSH2-2 disrupted parasites in less than 40 life cycles post-transfection, but not in PbMap2K disrupted controls or mosquito-passaged wild type parasites, which suggests a possible role for PbMSH2-2 in preventing microsatellite slippage, similar to MSH2 in other organisms. Our studies suggest that Plasmodium species may have evolved a unique variation on the highly conserved system of DNA repair compared to the mismatch repair systems in other eukaryotes.
AB - Although the mechanisms by which malaria parasites develop resistance to drugs are unclear, current knowledge suggests a main mechanism of resistance is the alteration of target enzymes by point mutation. In other organisms, defects in DNA mismatch repair have been linked to increased mutation rates and drug resistance. We have identified an unusual complement of mismatch repair genes in the Plasmodium genome. An initial functional test of two of these genes (PfMSH2-1 and PfMSH2-2) using a dominant mutator assay showed an elevation in mutation frequency with the PfMSH2-2 homolog, indirectly demonstrating a role for this gene in mismatch repair. We successfully disrupted PbMSH2-2 in the Plasmodium berghei laboratory isolate NK65, and showed that this gene is not essential for parasite growth in either the asexual (rodent) or sexual (mosquito) stages of the lifecycle. Although we observed some differences in levels of drug resistance between wild type and mutant parasites, no uniform trend emerged and preliminary evidence does not support a strong link between PbMSH2-2 disruption and dramatically increased drug resistance. We found microsatellite polymorphism in the PbMSH2-2 disrupted parasites in less than 40 life cycles post-transfection, but not in PbMap2K disrupted controls or mosquito-passaged wild type parasites, which suggests a possible role for PbMSH2-2 in preventing microsatellite slippage, similar to MSH2 in other organisms. Our studies suggest that Plasmodium species may have evolved a unique variation on the highly conserved system of DNA repair compared to the mismatch repair systems in other eukaryotes.
KW - DNA mismatch repair
KW - Drug resistance
KW - MSH2
KW - Malaria
KW - Plasmodium berghei
KW - Plasmodium falciparum
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U2 - 10.1016/j.molbiopara.2007.05.003
DO - 10.1016/j.molbiopara.2007.05.003
M3 - Article
C2 - 17583362
AN - SCOPUS:34447286827
SN - 0166-6851
VL - 155
SP - 18
EP - 25
JO - Molecular and Biochemical Parasitology
JF - Molecular and Biochemical Parasitology
IS - 1
ER -