Phenotypic characterization of a glucose transporter null mutant in Leishmania mexicana.
Glucose is a major source of energy and carbon in promastigotes of Leishmania mexicana, and its uptake is mediated by three glucose transporters whose genes are encoded within a single cluster. A null mutant in which the glucose transporter gene cluster was deleted by homologous gene replacement was generated previously and shown to grow more slowly than wild type promastigotes but not to be viable as amastigotes in primary tissue culture macrophages or in axenic culture. Further phenotypic characterization demonstrates that the null mutant is unable to import glucose, mannose, fructose, or galactose and that each of the three glucose transporter isoforms, LmGT1, LmGT2, and LmGT3, is capable of transporting each of these hexoses. Complementation of the null mutant with each isoform is able to restore growth in each of the four hexoses to wild type levels. Null mutant promastigotes are reduced in size to about 2/3 the volume of wild type parasites. In addition, the null mutants are significantly more sensitive to oxidative stress than their wild type counterparts. These results underscore the importance of glucose transporters in the parasite life cycle and suggest reasons for their non-viability in the disease-causing amastigote stage.
Rodriguez-Contreras
Dayana
D
Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, OR 97239, USA.
Feng
Xiuhong
X
Keeney
Kristie M
KM
Bouwer
H G Archie
HG
Landfear
Scott M
SM
D000818:Animals; D017125:Genes, Protozoan; D005816:Genetic Complementation Test; D006601:Hexoses / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007894:Leishmania mexicana / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D008264:Macrophages / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D018384:Oxidative Stress; D010641:Phenotype; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism*
D006601:Hexoses; D009004:Monosaccharide Transport Proteins; D020033:Protein Isoforms; D015800:Protozoan Proteins; C115490:glucose transporter, Leishmania