State Key Program of Microbiology and Department of Microbiology, College of Life Sciences, Nankai University, Tianjin, 300071, China.
Beijing Key Laboratory of Genetic Engineering Drug and Biotechnology, Institute of Biochemistry and Biotechnology, College of Life Sciences, Beijing Normal University, Beijing, China.
Microbiol Res. 2018 May;210:33-42. doi: 10.1016/j.micres.2018.03.001. Epub 2018 Mar 8.
Phosphatidylcholine (PC) is an important membrane component of the eukaryotic cell. In yeast fungi, two phospholipid methyltransferases catalyze consecutive steps of methylation in the formation of phosphatidylcholine from phosphatidylethanolamine. However, roles of phospholipid methyltransferases in filamentous fungi remains less investigated. We report here the characterization of two genes, choA and choC, that putatively encoded phospholipid methyltransferases in the taxol-producing fungus Pestalotiopsis microspora. Deletion of choC resulted in defects in PC production, vegetative growth and development of asexual structure. The mutant strains exhibited multiple morphological abnormalities, e.g. swollen hyphal tips and enhanced hyphal branching, and even mycelial autolysis. Some novel roles for the genes were also revealed, for instance, the deletion of either choC or choA impaired the development of pycnidia and conidia, the cell wall integrity. The mutant strains displayed a hypersensitivity to stress conditions, e.g. osmotic stress, cold and metal ions. The osmotic hypersensitivity indicates a crosstalk of PC pathways to other signaling pathways, such as the HOG pathway. Still more, choA, but not choC, was required for the production of secondary metabolites, e.g. pestalotiollide B, suggesting distinct roles of the two genes. This work would contribute to better understanding the function of phospholipid methyltransferases in fungi.
磷脂酰胆碱（PC）是真核细胞的重要膜成分。在酵母真菌中，两种磷脂酰转移酶催化磷脂酰乙醇胺形成磷脂酰胆碱的连续甲基化步骤。然而，磷脂酰转移酶在丝状真菌中的作用仍知之甚少。我们在这里报道了两个基因 choA 和 choC 的特征，它们在紫杉醇产生菌 Pestalotiopsis microspora 中可能编码磷脂酰转移酶。choC 的缺失导致 PC 产生、营养生长和无性结构发育的缺陷。突变株表现出多种形态异常，例如菌丝尖端肿胀和菌丝分支增强，甚至菌丝自溶。还揭示了这些基因的一些新作用，例如 choC 或 choA 的缺失会损害产孢盘和分生孢子的发育、细胞壁完整性。突变株对胁迫条件（如渗透压、冷和金属离子）表现出超敏性。渗透压超敏性表明 PC 途径与其他信号途径（如 HOG 途径）之间存在串扰。此外，choA 而不是 choC 是次级代谢产物（如 pestalotiollide B）产生所必需的，这表明这两个基因具有不同的作用。这项工作将有助于更好地理解磷脂酰转移酶在真菌中的功能。
