García-Rodriguez L J, Durán A, Roncero C
Instituto de Microbiología Bioquímica, Consejo Superior de Investigaciones Científicas/Universidad de Salamanca, 37007 Salamanca, Spain.
J Bacteriol. 2000 May;182(9):2428-37. doi: 10.1128/JB.182.9.2428-2437.2000.
We have isolated several Saccharomyces cerevisiae mutants resistant to calcofluor that contain mutations in the PBS2 or HOG1 genes, which encode the mitogen-activated protein kinase (MAPK) and MAP kinases, respectively, of the high-osmolarity glycerol response (HOG) pathway. We report that blockage of either of the two activation branches of the pathway, namely, SHO1 and SLN1, leads to partial resistance to calcofluor, while simultaneous disruption significantly increases resistance. However, chitin biosynthesis is independent of the HOG pathway. Calcofluor treatment also induces an increase in salt tolerance and glycerol accumulation, although no activation of the HOG pathway is detected. Our results indicate that the antifungal effect of calcofluor depends on its binding to cell wall chitin but also on the presence of a functional HOG pathway. Characterization of one of the mutants isolated, pbs2-14, revealed that resistance to calcofluor and HOG-dependent osmoadaptation are two different physiological processes. Sensitivity to calcofluor depends on the constitutive functionality of the HOG pathway; when this is altered, the cells become calcofluor resistant but also show very low levels of basal salt tolerance. Characterization of some multicopy suppressors of the calcofluor resistance phenotype indicated that constitutive HOG functionality participates in the maintenance of cell wall architecture, a conclusion supported by the antagonism observed between the protein kinase and HOG signal transduction pathways.
我们分离出了几种对荧光增白剂具有抗性的酿酒酵母突变体,这些突变体在PBS2或HOG1基因中存在突变,这两个基因分别编码高渗甘油应答(HOG)途径的丝裂原活化蛋白激酶(MAPK)和MAP激酶。我们报告称,该途径的两个激活分支SHO1和SLN1中的任何一个被阻断,都会导致对荧光增白剂产生部分抗性,而同时破坏这两个分支则会显著增加抗性。然而,几丁质生物合成独立于HOG途径。荧光增白剂处理还会诱导耐盐性增加和甘油积累,尽管未检测到HOG途径的激活。我们的结果表明,荧光增白剂的抗真菌作用不仅取决于其与细胞壁几丁质的结合,还取决于功能性HOG途径的存在。对分离出的一个突变体pbs2-14的表征显示,对荧光增白剂的抗性和HOG依赖性渗透适应是两个不同的生理过程。对荧光增白剂的敏感性取决于HOG途径的组成型功能;当这种功能发生改变时,细胞对荧光增白剂产生抗性,但基础耐盐水平也非常低。对一些荧光增白剂抗性表型的多拷贝抑制子的表征表明,组成型HOG功能参与维持细胞壁结构,这一结论得到了蛋白激酶和HOG信号转导途径之间拮抗作用的支持。