The Rho1 GTPase-activating Protein CgBem2 Is Required for Survival of Azole Stress in Candida glabrata
The Rho1 GTPase-activating Protein CgBem2 Is Required for Survival of Azole Stress in Candida glabrata
复制标题
DOI：
10.1074/jbc.m111.264671
复制
发表时间：
2011-09-30
影响因子：
4.8
通讯作者：
Kaur, Rupinder
中科院分区：
文献类型：
--
作者：
Borah, Sapan;Shivarathri, Raju;Kaur, Rupinder
侵袭性真菌感染是全世界新生儿、危重病人和免疫功能低下患者常见的临床并发症。念珠菌是播散性真菌感染的主要原因，其中白色念珠菌是最常见的菌种。光滑假丝酵母菌是引起念珠菌血症的第二/第三常见原因，它显示出对广泛使用的抗真菌药物氟康唑的敏感性降低。在这里，我们介绍了9134个光滑线虫Tn7插入突变体在氟康唑存在下存活率改变的发现。我们已经确定了RNA聚合酶II介体复合体的两个组分，Rho GTP酶介导的信号级联的三个角色，以及与肌动蛋白细胞骨架生物发生和麦角固醇生物合成有关的两个蛋白质，这两个蛋白质是维持氟康唑胁迫下的生存所必需的。我们发现，暴露在氟康唑导致蛋白激酶C(PKC)介导的细胞壁完整性途径的激活。我们的数据表明，含有RhoGAP(GTPase激活蛋白)结构域的蛋白CgBem2的破坏会导致出芽缺陷、对唑的敏感性以及CgRho1调节的CgPkc1信号级联和细胞壁相关表型的结构性激活。突变株Cgbem2Delta经氟康唑处理后的活力损失可被蛋白激酶C抑制剂星形孢子素部分挽救。此外，我们提出的证据表明，CgBEM2是编码多药外排泵基因转录激活所必需的，以响应氟康唑的暴露。最后，我们报道了Hsp90抑制剂格尔达那霉素使氟康唑成为光滑念珠菌中的杀菌剂。
Invasive fungal infections are common clinical complications of neonates, critically ill, and immunocompromised patients worldwide. Candida species are the leading cause of disseminated fungal infections, with Candida albicans being the most prevalent species. Candida glabrata, the second/third most common cause of candidemia, shows reduced susceptibility to a widely used antifungal drug fluconazole. Here, we present findings from a screen of 9134 C. glabrata Tn7 insertion mutants for altered survival profiles in the presence of fluconazole. We have identified two components of RNA polymerase II mediator complex, three players of Rho GTPase-mediated signaling cascade, and two proteins implicated in actin cytoskeleton biogenesis and ergosterol biosynthesis that are required to sustain viability during fluconazole stress. We show that exposure to fluconazole leads to activation of the protein kinase C (PKC)-mediated cell wall integrity pathway in C. glabrata. Our data demonstrate that disruption of a RhoGAP (GTPase activating protein) domain-containing protein, CgBem2, results in bud-emergence defects, azole susceptibility, and constitutive activation of CgRho1-regulated CgPkc1 signaling cascade and cell wall-related phenotypes. The viability loss of Cgbem2 Delta mutant upon fluconazole treatment could be partially rescued by the PKC inhibitor staurosporine. Additionally, we present evidence that CgBEM2 is required for the transcriptional activation of genes encoding multidrug efflux pumps in response to fluconazole exposure. Last, we report that Hsp90 inhibitor geldanamycin renders fluconazole a fungicidal drug in C. glabrata.