MATING TYPE AND VIRULENCE IN CRYPTOCOCCUS NEOFORMANS

描述(改编自申请人的摘要)：隐球菌 新生杆菌是一种担子菌，可导致生命危险。 感染。这在艾滋病患者中可能尤其严重，他们在 感染风险最高，通常需要终生抗真菌药物 预防措施。Matpha交配型是已知的四种毒力之一 新生葡萄球菌的致病因素。除了毒力更强之外。MATAlpha 与MATA细胞不同的是，细胞还可以在 单倍体状态，称为单核果。这项工作的主要目标是 建议确定MATAlpha之间的分子和遗传联系 交配型、单核结实和致病力。这一目标要求 对新生隐翅虫交配的基本了解，并将在 四个具体目标。这项研究的第一个目的将是了解 酿酒酵母STE12的Matpha同源基因STE12a的功能 吉恩。STE12a将被作为潜在的关键毒力因子进行研究，因为它 作为转录激活因子的角色使其能够相互作用并诱导 其他基因的表达。STE12a可以诱导的一个基因是CNLAC1，一种 已证实的致病因子。STE12a在毒力中的作用以及 可能与黑色素和胶囊产生相关基因的相互作用， 交配和单核结实将被研究。第二个目标是 本研究旨在分离MATα交配型基因座。物理 不育突变体的基因定位和互补将允许 鉴定阿尔法特异基因。然后将对这些基因进行测试 关于它们在使用小鼠模型的毒力中所扮演的角色以及它们在 交配和单核果。这项研究的第三个目标将是 研究单核细胞结实的分子基础。这种表型 提供了在没有 相反的交配类型，并在一定程度上解释了倾向于 环境中的MATAlpha细胞。诱导或抑制的因素 将对单核果进行评估。为了改善表型 并使这种现象更容易受到遗传因素的影响 分析，将进行菌株改良，以筛选出具有 高级菌丝表型。遗传标记将被引入到这些 通过诱变将产生菌株和菌丝阴性突变株。这些 突变株将与基因组DNA文库互补，以便分离 单核果实相关基因，然后可以测试它们的作用 在交配和毒性方面。最后，这项研究的最后目的将是 分离MATA基因座。鉴于MATA细胞的毒力降低和 一些保守的交配型基因的配对特异性， Mata中包含的信息将与 并将有助于理解交配和致病力 新生革兰氏菌。

DESCRIPTION (Adapted from the applicant's abstract): Cryptococcus neoformans is a basidiomycetous fungus which can cause life threatening infections. It can be especially serious in AIDS patients who are at the highest risk for infection and often require life-long antifungal prophylaxis. The MATalpha mating type is one of the four known virulence factors of C. neoformans. In addition to being more virulent. MATalpha cells, unlike MATa cells, can also produce an extensive hyphal phase in the haploid state called monokaryotic fruiting. The main objective of this proposal is to identify the molecular and genetic links between the MATalpha mating type, monokaryotic fruiting, and virulence. This objective requires a basic understanding of mating in C. neoformans and will be accomplished in four specific aims. The first aim of this study will be to understand the function of STE12a, a MATalpha-specific homolog of the S. cerevisiae STE12 gene. STE12a will be studied as a potential key virulence factor since its role as a transcriptional activator allows it to interact and induce expression of other genes. One gene which STE12a can induce is CNLAC1, a proven virulence factor. The role of STE12a in virulence, as well as possible interactions with genes involved in melanin and capsule production, mating, and monokaryotic fruiting will be investigated. The second aim of this study will be to isolate the MAT alpha mating type locus. Physical mapping of the locus and complementation of sterile mutants will allow the identification MAT alpha-specific genes. These genes will then be tested for their roles in virulence using the mouse model as well as their roles in mating and monokaryotic fruiting. The third aim of this study will be to investigate the molecular basis of monokaryotic fruiting. This phenotype provides the mechanism for producing infectious particles in the absence of the opposite mating type and explains, in part, the extreme bias in favor of MATalpha cells in the environment. Factors which induce or repress monokaryotic fruiting will be evaluated. In order to improve the phenotype of hyphae production and make this phenomenon more amenable to genetic analysis, strain improvement will be performed to select for strains with an advanced hyphal phenotype. Genetic markers will be introduced into these strains and hyphal-negative mutants will be created by mutagenesis. These mutants will be complemented with genomic DNA libraries in order to isolate monokaryotic fruiting-related genes which can then be tested for their roles in mating and virulence. Finally, the last aim of this study will be to isolate the MATa locus. in light of the reduced virulence of MATa cells and the MATa-specificity of some of the conserved mating type genes, the information contained in MATa will contrast well with the information in MATalpha and will contribute to the understanding of mating and virulence in C. neoformans.