Comparative Genomics of Histoplasma and Blastomyces

描述（由申请人提供）：温度诱导的从腐生霉菌形式到寄生酵母形式的转变对于二态真菌的疾病建立是必不可少的，但是调节这种转变和解释酵母毒力的基因知之甚少。荚膜组织胞浆菌和皮炎芽孢菌是系统发育上关系最密切的二态真菌，它们在世界范围内引起疾病，并代表着日益严重的人类健康问题。分子遗传工具的发展使这两种真菌在遗传上易于处理，并为酵母阶段上调基因在毒力中的作用提供了第一个确凿的证据-在荚衣孢子虫中CBP1和在皮炎芽孢杆菌中BAD1。我们建议在此鉴定和比较这两种药物中所有的酵母阶段上调基因，然后探索这些基因的一个选定子集的功能作用。我们假设这两种真菌将表现出进化上共享的和不同的基因，这些基因调节形态发生和致病性。一个由三个领先实验室组成的联盟将结合他们在大规模基因组学、分子遗传学和真菌发病机理方面的经验；由此产生的合作将使用基于微阵列的方法来识别和分析潜在的毒力相关基因。

DESCRIPTION (provided by applicant): The temperature-induced transition from the saprophytic mold form to the parasitic yeast form is essential for the establishment of disease by dimorphic fungi, but the genes that regulate this switch and account for yeast virulence are poorly understood. Histoplasma capsulatum and Blastomyces dermatitidis are phylogenetically the most closely related among the dimorphic fungi that cause disease worldwide and represent a growing human health problem. Development of molecular genetic tools has rendered both these fungi genetically tractable and provided the first firm evidence for the role of yeast phase-upregulated genes in virulence - CBP1 in H. capsulatum and BAD1 in B. dermatitidis. We propose here to identify and compare all of the yeast phase-upregulated genes from these two agents, then explore the functional roles of a selected subset of these genes. We hypothesize that these two fungi will exhibit both evolutionarily shared and distinct genes that regulate morphogenesis and pathogenicity. A consortium of three leading labs will combine their experience with large-scale genomics, molecular genetics, and fungal pathogenesis; the resulting collaboration will use a microarray-based approach to identify and analyze potential virulence-associated genes. Our specific aims are to: I. Sequence the B. dermatitidis genome to approximately 3-fold coverage for comparson to H. capsulatum. II. Identify yeast phase-upregulated genes using microarrays and informatics, and prioritize genes for virulence-related studies. III. Functionally characterize in H. capsulatum and B. dermatitidis 16 to 20 of the prioritized genes by creating isogenic null mutants for investigation in animal and cell culture models of infection, exploiting lacZ and gfp reporters to monitor regulation and expression of the genes, and employing microarrays to identify other genes that are coordinately regulated. Findings from this work will provide substantial new knowledge about the biology and pathogenesis of systemic fungal diseases and may identify among conserved genes many potential new drug targets.