Peñalva Miguel A, Tilburn Joan, Bignell Elaine, Arst Herbert N
Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Cientificas, Ramiro de Maeztu, Madrid, Spain.
Trends Microbiol. 2008 Jun;16(6):291-300. doi: 10.1016/j.tim.2008.03.006. Epub 2008 May 3.
Many fungi grow over a wide pH range and their gene expression is tailored to the environmental pH. In Aspergillus nidulans, the transcription factor PacC, an activator of genes expressed in alkaline conditions and a repressor of those expressed in acidic conditions, undergoes two processing proteolyses, the first being pH-signal dependent and the second proteasomal. Signal transduction involves a 'go-between' connecting two complexes, one of which comprises two plasma membrane proteins and an arrestin and the other comprises PacC, a cysteine protease, a scaffold and endosomal components. The Saccharomyces cerevisiae PacC orthologue, Rim101p, differs in that it does not undergo the second round of proteolysis and it functions directly as a repressor only. PacC/Rim101-mediated pH regulation is crucial to fungal pathogenicity.
许多真菌能在较宽的pH范围内生长，其基因表达会根据环境pH进行调整。在构巢曲霉中，转录因子PacC是碱性条件下表达基因的激活剂和酸性条件下表达基因的抑制剂，它会经历两次加工性蛋白水解，第一次是pH信号依赖性的，第二次是蛋白酶体介导的。信号转导涉及一个连接两个复合物的“中间物”，其中一个复合物由两种质膜蛋白和一种抑制蛋白组成，另一个复合物由PacC、一种半胱氨酸蛋白酶、一个支架和内体成分组成。酿酒酵母的PacC同源物Rim101p则不同，它不会经历第二轮蛋白水解，仅直接作为一种抑制剂发挥作用。PacC/Rim101介导的pH调节对真菌致病性至关重要。
