| Sujet | fungal protein; green fluorescent protein; myosin I; transcription factor; allele; Candida albicans; culture medium; fungal gene; gene expression regulation; gene inactivation; gene regulatory network; genetic transcription; genetics; metabolism; phenotype; physiology; promoter region; real time polymerase chain reaction; regulator gene; Alleles; Candida albicans; Culture Media; Fungal Proteins; Gene Expression Regulation, Fungal; Gene Knockout Techniques; Gene Regulatory Networks; Genes, Mating Type, Fungal; Genes, Switch; Green Fluorescent Proteins; Myosin Type I; Phenotype; Promoter Regions, Genetic; Real-Time Polymerase Chain Reaction; Transcription Factors; Transcription, Genetic; Candida albicans |
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| Résumé | The Candida albicans MYO5 gene encodes myosin I, a protein required for the formation of germ tubes and true hyphae. Because the polarized growth of opaque-phase cells in response to pheromone results in mating projections that can resemble germ tubes, we examined the role of Myo5p in this process. We localized green fluorescent protein (GFP)-tagged Myo5p in opaquephase cells of C. albicans during both bud and shmoo formation. In vegetatively growing opaque cells, Myo5p is found at sites of bud emergence and bud growth, while in pheromone-stimulated cells, Myo5p localizes at the growing tips of shmoos. Intriguingly, cells homozygous for MTLa in which the MYO5 gene was deleted failed to switch efficiently from the white phase to the opaque phase, although ectopic expression of WOR1 from the MET3 promoter can convert myo5 mutants into mating-competent opaque cells. However, when WOR1 expression was shut off, the myo5-defective cells rapidly lost both their opaque phenotype and mating competence, suggesting that Myo5p is involved in the maintenance of the opaque state. When MYO5 is expressed conditionally in opaque cells, the opaque phenotype, as well as the mating ability of the cells, becomes unstable under repressive conditions, and quantitative real-time PCR demonstrated that the shutoff of MYO5 expression correlates with a dramatic reduction in WOR1 expression. It appears that while myosin I is not directly required for mating in C. albicans, it is involved in WOR1 expression and the white-opaque transition and thus is indirectly implicated in mating. © 2012, American Society for Microbiology. All Rights Reserved. |
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