Triazole antifungals are the primary therapeutic option against invasive aspergillosis. However, resistance to azoles has increased dramatically over the last decade. Azole resistance is known to primarily occur due to point mutations in the azole target protein Cyp51A, one of two paralogous 14-α sterol demethylases found in Aspergillus fumigatus. Despite the importance of Cyp51A, little is known about the function of its paralog, Cyp51B, and the behavior of these proteins within the cell or their functional interrelationship. In this study, we addressed two important aspects of the Cyp51 proteins: (i) we characterized their localization patterns under normal growth versus stress conditions, and (ii) we determined how the proteins compensate for each other’s absence and respond to azole treatment. Both the Cyp51A and Cyp51B proteins were found to localize in distinct endoplasmic reticulum (ER) domains, including the perinuclear ER and the peripheral ER. Occasionally, the Cyp51 proteins concentrated in the peripheral ER network of tubules along the hyphal septa and at the hyphal tips. Exposure to voriconazole, caspofungin, and Congo red led to significant increases in fluorescence intensity in these alternative localization sites, indicative of Cyp51 protein translocation in response to cell wall stress. Furthermore, deletion of either Cyp51 paralog increased susceptibility to voriconazole, though a greater effect was observed following deletion of cyp51A, indicating a compensatory response to stress conditions.

中文翻译：

---

烟曲霉Cyp51A和Cyp51B蛋白在功能上具有补偿功能，并且在抗真菌剂和细胞壁抑制剂的响应中差异化定位。

三唑类抗真菌药是抗侵袭性曲霉病的主要治疗选择。但是，在过去十年中，对唑类的抗药性急剧增加。已知对偶氮唑的抗性主要是由于在烟曲霉中发现的两种靶基因14-α甾醇脱甲基酶之一的吡咯靶蛋白Cyp51A中的点突变引起的。尽管Cyp51A具有重要意义，但对其旁系同源物Cyp51B的功能以及这些蛋白在细胞内的行为或功能相互关系知之甚少。在这项研究中，我们研究了Cyp51蛋白的两个重要方面：（i）在正常的生长与胁迫条件下表征了它们的定位模式；（ii）我们确定了蛋白如何补偿彼此的缺失并响应吡咯处理。发现Cyp51A和Cyp51B蛋白都位于不同的内质网（ER）域中，包括核周ER和外周ER。有时，Cyp51蛋白集中在沿菌丝间隔和菌丝尖端的肾小管周围ER网络中。暴露于伏立康唑，卡泊芬净，刚果红和刚果红导致这些替代性定位位点的荧光强度显着增加，表明Cyp51蛋白易位，响应细胞壁压力。此外，删除任何一个Cyp51旁系同源物都增加了对伏立康唑的敏感性，尽管在删除CYP51后观察到了更大的作用。cyp51A，表示对压力条件的补偿性反应。