Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229, USA.
Mol Microbiol. 2011 Feb;79(4):990-1007. doi: 10.1111/j.1365-2958.2010.07501.x.
Cryptococcus neoformans typically grows in a yeast-like morphology; however, under specific conditions the fungus can produce hyphae that are either dikaryotic or monokaryotic. In this study, we developed a simple method for inducing robust monokaryotic fruiting and combined the assay with Agrobacterium tumefaciens insertional mutagenesis to screen for hyphal mutants. A C. neoformans homologue of the Saccharomyces cerevisiae STE50 gene was identified and characterized. STE50 was found to be required for sexual reproduction and monokaryotic fruiting. Ste50p has conserved SAM and RA domains, as well as two SH3 domains specific to basidiomycetous Ste50 proteins. Analysis of protein-protein interaction showed that Ste50p can interact with Ste11p and Ste20p, and epistasis experiments placed STE50 between STE20 and STE11. Genetic analysis of the role of STE50 in sexual reproduction showed that it was required for all steps, from response to pheromone to production of hyphae. Analysis of the effect of individual Ste50p domains on sexual reproduction and monokaryotic fruiting revealed domain-specific effects for both processes. This study revealed that the C. neoformans STE50 gene has both conserved and novel functions during sexual reproduction and monokaryotic fruiting, and these functions are domain-dependent.
新型隐球菌通常以酵母样形态生长；然而，在特定条件下，真菌可以产生双核或单核的菌丝。在这项研究中，我们开发了一种诱导强单核结实的简单方法，并将该方法与根癌农杆菌插入突变相结合，以筛选菌丝突变体。鉴定并表征了新型隐球菌中酿酒酵母 STE50 基因的同源物。发现 STE50 基因对于有性生殖和单核结实是必需的。Ste50p 具有保守的 SAM 和 RA 结构域，以及两个特异性存在于担子菌 Ste50 蛋白中的 SH3 结构域。蛋白-蛋白相互作用分析表明，Ste50p 可以与 Ste11p 和 Ste20p 相互作用，并且上位实验将 STE50 置于 STE20 和 STE11 之间。STE50 在有性生殖中的作用的遗传分析表明，它是从对信息素的反应到产生菌丝的所有步骤所必需的。分析 Ste50p 各个结构域对有性生殖和单核结实的影响表明，这两个过程都存在结构域特异性效应。这项研究揭示了新型隐球菌 STE50 基因在有性生殖和单核结实过程中具有保守和新颖的功能，并且这些功能依赖于结构域。
