Avenot Hervé, Simoneau Philippe, Iacomi-Vasilescu Béatrice, Bataillé-Simoneau Nelly
Faculté des Sciences, UMR PaVé A77, 2 Bd Lavoisier, 49045 Angers Cedex, France.
Curr Genet. 2005 Apr;47(4):234-43. doi: 10.1007/s00294-005-0568-2. Epub 2005 Mar 12.
Highly iprodione- and fludioxonil-resistant field and laboratory isolates of A. brassicicola were found to be either moderately sensitive or tolerant to osmotic stress. AbNIK1, a two-component histidine kinase gene, was isolated from a fungicide-sensitive strain. The predicted protein possessed the six tandem amino acid repeats at the N-terminal end, which is a landmark of osmosensor histidine kinases from filamentous fungi. A comparison of the nucleic acid sequences of the AbNIK1 gene from fungicide-sensitive and fungicide-resistant isolates revealed the presence of mutations in six of the seven resistant strains analyzed. Null mutants were all found to be moderately sensitive to osmotic stress, indicating that they are similar to Neurospora crassa Type I os-1 mutants. Only one mutation, corresponding to a single amino acid change within the H-box of the kinase domain, was found in an osmotolerant strain. These results suggest that AbNIK1p participates in osmoregulation and that expression of the fully functional enzyme is essential for dicarboximide and phenylpyrrole antifungal activities.
研究发现，对异菌脲和咯菌腈具有高度抗性的芸苔链格孢田间和实验室分离株对渗透胁迫表现出中度敏感或耐受。从一个对杀菌剂敏感的菌株中分离出了双组分组氨酸激酶基因AbNIK1。预测的蛋白质在N末端具有六个串联氨基酸重复序列，这是丝状真菌渗透传感器组氨酸激酶的一个标志。对杀菌剂敏感和抗性分离株的AbNIK1基因核酸序列进行比较，发现在分析的七个抗性菌株中有六个存在突变。所有缺失突变体均被发现对渗透胁迫中度敏感，表明它们与粗糙脉孢菌I型os-1突变体相似。在一个耐渗透菌株中仅发现一个突变，对应于激酶结构域H盒内的单个氨基酸变化。这些结果表明，AbNIK1p参与渗透调节，并且全功能酶的表达对于二羧酰亚胺和苯基吡咯类抗真菌活性至关重要。
