Functional characterization and virulence study of ADE8 and GUA1 genes involved in the de novo purine biosynthesis in Candida albicans.
Candida albicans is the principal human fungal pathogen that leads to life-threatening mycoses worldwide. To study its pathobiology, we characterized genes for two enzymes involved in the de novo purine biosynthesis pathway: ADE8 (encoding phosphoribosylglycinamide formyl-transferase) and GUA1 (GMP synthase). Heterozygous and homozygous disruption strains were constructed for both genes. We found that ADE8 and GUA1 are conditionally essential; i.e. can be bypassed in the presence of exogenous adenine and guanine, respectively, and that ADE8 plays an additional role in the C1-folate pool. Furthermore, the heterozygotes of ADE8/ade8 and GUA1/gua1 were hypersensitive to methotrexate (an inhibitor of de novo synthesis of tetrahydrofolate) and 6-azauracil (a known inhibitor of the IMP dehydrogenase involved in GMP biosynthesis), respectively. In a murine model of systemic candidiasis, the virulence of both heterozygous strains was marginally attenuated, while the ade8/ade8 and gua1/gua1 strains were completely avirulent. Our results and those of others indicate that many conditional essential genes involved in different biosynthesis pathways are required for systemic candidiasis, likely due to the host nutritional constraints imposed on the pathogen.
Jiang
Linghuo
L
Tianjin Research Center of Basic Medical Sciences, Tianjin Medical University, Tianjin, China.
Zhao
Jingwen
J
Guo
Rui
R
Li
Jing
J
Yu
Liquan
L
Xu
Deming
D
D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000472:pathogenicity*; D002177:Candidiasis / Q000382:microbiology*; D019731:Carbon-Nitrogen Ligases / Q000235:genetics / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006801:Humans; D008297:Male; D008727:Methotrexate / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D008826:Microbial Sensitivity Tests; D051026:Phosphoribosylglycinamide Formyltransferase / Q000235:genetics / Q000378:metabolism; D011687:Purines / Q000096:biosynthesis*; D014498:Uracil / Q000031:analogs & derivatives / Q000494:pharmacology; D014774:Virulence
D000935:Antifungal Agents; D005656:Fungal Proteins; D011687:Purines; D014498:Uracil; D051026:Phosphoribosylglycinamide Formyltransferase; D019731:Carbon-Nitrogen Ligases; C020828:GMP synthase (glutamine-hydrolyzing); C100248:azauracil; C030985:purine; D008727:Methotrexate