Nemecek Julie C, Wüthrich Marcel, Klein Bruce S
Department of Pediatrics, University of Wisconsin-Madison School of Medicine and Public Health, Madison, Wisconsin, USA.
Methods Enzymol. 2007;422:465-87. doi: 10.1016/S0076-6879(06)22024-X.
Systemic dimorphic fungi include six phylogenetically related ascomycetes. These organisms grow in a mold form in the soil on most continents around the world. After the mold spores, which are the infectious particles, are inhaled into the lung of a susceptible mammalian host, they undergo a morphological change into a pathogenic yeast form. The ability to convert to the yeast form is essential for this class of fungal agents to be pathogenic and produce disease. Temperature change is one key stimulus that triggers the phase transition from mold (25 degrees ) to yeast (37 degrees ). Genes that are expressed only in the pathogenic yeast form of these fungi have been identified to help explain how and why this phase transition is required for virulence. However, the regulators of yeast-phase specific genes, especially of phase transition from mold to yeast, have remained poorly understood. We used Agrobacterium-mediated gene transfer for insertional mutagenesis to create mutants that are defective in the phase transition and to identify genes that regulate this critical event. We discovered that a hybrid histidine kinase senses environmental signals such as temperature and regulates phase transition, dimorphism, and virulence in members of this fungal family. This chapter describes our approach to the identification and analysis of this global regulator.
全身性二态真菌包括六种系统发育相关的子囊菌。这些生物体在世界上大多数大陆的土壤中以霉菌形式生长。作为感染性颗粒的霉菌孢子被吸入易感哺乳动物宿主的肺部后，会发生形态变化，转变为致病性酵母形式。转变为酵母形式的能力对于这类真菌病原体致病和引发疾病至关重要。温度变化是触发从霉菌（25摄氏度）到酵母（37摄氏度）相变的一个关键刺激因素。已鉴定出仅在这些真菌的致病性酵母形式中表达的基因，以帮助解释这种相变对于毒力的作用方式和原因。然而，酵母阶段特异性基因的调节因子，尤其是从霉菌到酵母的相变调节因子，仍知之甚少。我们利用农杆菌介导的基因转移进行插入诱变，以创建在相变方面有缺陷的突变体，并鉴定调节这一关键事件的基因。我们发现一种杂合组氨酸激酶能感知温度等环境信号，并调节该真菌家族成员的相变、二态性和毒力。本章描述了我们鉴定和分析这种全局调节因子的方法。
