Characterization of Cryptococcus neoformans SET2 homologue
| Autor: | Ci-Hong Liou, 劉啟宏 |
|---|---|
| Rok vydání: | 2006 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 94 Cryptococcus neoformans is an opportunistic human fungal pathogen which primarily infects immunocompromised patients, such as AIDS, organ transplant, and cancer chemotherapy. Due to its available completed genome sequences, well-developed transformation systems, and robust animal models, C. neoformans has become an excellent model system for studying the virulence and physiological processes in fungi. C. ceoformans is a heterothallic basidiomycete, and exists predominantly as a haploid yeast under routinely laboratory culture condition. When opposite mating types strains, MATa and MATα, are co-cultured under nitrogen starvation condition, the conjugation tubes are formed and fused to poduce the sexual dikaryotic filaments. Our prior studies have shown that blue light inhibits the sexual filamentation via the Cwc1 and Cwc2 proteins in C. neoformans. To reveal the molecular mechanisms of blue light photoresponses, genome-wide random insertional mutagenesis by Agrobacterium-mediated transformation was employed to identify genes involved in the light inhibition of filamentation. We have identified 64 strains from 4132 transformants, of which restore the filamentation phenotype of the CWC1 overexpression strain under constant light condition. One of these strains, AS31 strain, was found that T-DNA was integrated at the coding region of Saccharomyces cerevisiae SET2 homologue. In this study, we demonstrated that the suppression of light-dependent phenotype of the CWC1 overexpression strain was caused by disruption of SET2 function in the AS31 strain. Furthermore, overexpression and disruption of SET2 gene in the wild-type strain background were conducted. Overexpression or disruption of SET2 in the MATα strain both displayed reduced sexual filamentation and haploid fruiting under light or dark conditions; however, the filamentation of the MATa set2 mutant and MATa SET2 overexpression strain were all comparable to the MATa wild-type strain. Additionally, the discrepancies between the sexual and haploid filamentation were also observed in the MATα cwc1 set2 double mutants. Taken together, our results suggest that SET2 gene functions to regulate the filamentation pathway, however, further study is needed to address its roles in different mating type strain. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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