MATING TYPE AND VIRULENCE IN CRYPTOCOCCUS NEOFORMANS

性状（改编自申请人摘要）：隐球菌 neoformans是一种担子菌真菌， 感染. 这可能是特别严重的艾滋病患者谁是在 感染风险最高，通常需要终身抗真菌治疗 预防。 MAT α交配型是四种已知的毒力之一 因子C.新人类 除了毒性更强之外。 MAT alpha 细胞，不像MATa细胞，也可以产生一个广泛的菌丝期， 单倍体状态称为单核结实。 的主要目标 我们的建议是确定MAT α之间的分子和遗传联系， 交配型、单核结实和毒力。 这一目标需要 对C.新形式的人，并将在 四个具体目标。 本研究的第一个目的是了解 STE12a是S.酿酒酵母STE12 基因 STE12a将作为潜在的关键毒力因子进行研究，因为其 作为转录激活因子的作用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CNLAC 1， 毒力因子。 STE12 a在毒力中的作用，以及 可能与黑色素和胶囊产生相关的基因相互作用， 交配和单核子实体将被研究。 的第二个目的 本研究将分离MAT α交配型基因座。 物理 基因座的定位和不育突变体的互补将允许 鉴定MAT α特异性基因。 然后这些基因将被测试 它们在使用小鼠模型的毒力中的作用，以及它们在 交配和单核结实。 本研究的第三个目标是 探讨单核子实体形成的分子基础。 这种表型 提供了在不存在感染性颗粒的情况下产生感染性颗粒的机制， 相反的交配类型，并解释了，部分，极端的偏见，有利于 环境中的MAT α细胞。 诱发或抑制的因素 评价单核子实体。 为了改善表型 使这种现象更容易遗传 分析，将进行菌株改良以选择具有 高级菌丝表型。 遗传标记将被引入这些 菌株和菌丝阴性突变体将通过诱变产生。 这些 突变体将与基因组DNA文库互补，以分离 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，本研究的最后一个目的是 分离MATa基因座。 鉴于MATa细胞的毒力降低， 一些保守的交配型基因的MATA特异性， MATa中包含的信息将与 MATalpha的研究将有助于理解交配和毒力， C.新人类

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.