Subcellular localization of Sur7 and its pleiotropic effect on cell wall integrity, multiple stress responses, and virulence ofBeauveria bassiana
Subcellular localization of Sur7 and its pleiotropic effect on cell wall integrity, multiple stress responses, and virulence ofBeauveria bassiana
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Sur7 的亚细胞定位及其对白僵菌细胞壁完整性、多重应激反应和毒力的多效作用
DOI：
10.1007/s00253-020-10736-3
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发表时间：
2020
影响因子：
5
通讯作者：
Feng Ming-Guang
中科院分区：
文献类型：
--
作者：
Zhang Long-Bin;Tang Li;Guan Yi;Feng Ming-Guang
Sur7 是构成 MCC（Can1 的膜区室，充当精氨酸/H+同向转运体）的多种蛋白质之一，MCC 是一个关键的膜结构域，可以在质膜上形成点状异构体点，并在模型酵母中执行多种功能，但在丝状真菌中仍然知之甚少。在这里，具有典型 SUR7 结构域和四个跨膜结构域的 Sur7 同源物被证明位于分生孢子囊泡中并进入液泡，并在昆虫病原真菌白僵菌的菌丝生长过程中偶尔出现在外围膜上，这表明 Sur7 参与了与质膜和液泡相关的细胞事件。 sur7的缺失导致分生孢子能力降低和分生孢子质量受损，其特点是发芽减慢、毒力减弱和碳水化合物表位（β-N-乙酰氨基葡萄糖和唾液酸）减少。此外，由于几丁质和中性碳水化合物含量减少约 70%，碱溶性碳水化合物含量适度增加，缺失突变体的菌丝细胞壁严重受损。因此，缺失突变体对三种细胞壁干扰化学物质（刚果红、卡尔科弗洛白和 SDS）和抗真菌药物（卡泊芬净）变得更加敏感，并且令人惊讶地表现出对 H2O2 氧化应激的超敏感性以及对 NaCl 或山梨醇渗透应激的敏感性增加。它对 H2O2 的超敏反应与 H2O2 分解所需的关键过氧化氢酶基因的转录抑制有关。这些发现揭示了 Sur7 参与 MCC/eisosome 和液泡事件，因此在白僵菌中充当分生孢子能力、细胞壁完整性、多重胁迫耐受性和毒力的维持者。要点 • Sur7 是白僵菌关键膜域MCC 的组成部分。 • Sur7 主要位于液泡中，偶尔位于外周膜上。 • Sur7 是细胞壁完整性所必需的，并且对白僵菌具有多效性作用。
Sur7 is one of multiple proteins constituting MCC (membrane compartment of Can1 acting as an arginine/H+symporter), a crucial membrane domain that can form punctuate eisosome spots on the plasma membrane and execute diverse functions in model yeast but remains poorly understood in filamentous fungi. Here, a Sur7 homolog bearing a typical SUR7 domain and four transmembrane domains was shown to localize in the conidial vesicles and enter vacuoles and appear sporadically on the periphery membrane during hyphal growth in the insect-pathogenic fungus Beauveria bassiana, implicating an involvement of Sur7 in cellular events linked to both plasma membrane and vacuoles. Deletion of sur7 resulted in reduced conidiation capacity and impaired conidial quality, which was featured by slower germination, attenuated virulence, and reduced carbohydrate epitopes (β-N-acetylglucosamine and sialic acids). Also, the hyphal cell walls of the deletion mutant were severely impaired due to ~ 70% reductions in chitin and neutral carbohydrate contents and a moderate increase in alkali-soluble carbohydrate content. Consequently, the deletion mutant became more sensitive to three cell wall perturbing chemicals (Congo red, calcofluor white, and SDS) and an antifungal drug (caspofungin) and surprisingly showed a hypersensitivity to oxidative stress of H2O2and an increased sensitivity to osmotic stress of NaCl or sorbitol. Its hypersensitivity to H2O2was associated with transcriptional repression of critical catalase genes required for H2O2decomposition. These findings unveil that Sur7 takes part in both MCC/eisosome and vacuolar events and hence acts as a sustainer of conidiation capacity, cell wall integrity, multiple stress tolerance, and virulence in B. bassiana. Key points • Sur7 is a component of the crucial membrane domain MCC in Beauveria bassiana. • Sur7 localizes mainly in the vacuoles and sporadically on the periphery membrane. • Sur7 is required for cell wall integrity and has a pleiotropic effect on B. bassiana.