Regulation of azole drug susceptibility by Candida albicans protein kinase CK2
Regulation of azole drug susceptibility by Candida albicans protein kinase CK2
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DOI：
10.1111/j.1365-2958.2005.04562.x
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发表时间：
2005-04-01
影响因子：
3.6
通讯作者：
Mitchell, AP
中科院分区：
文献类型：
--
作者：
Bruno, VM;Mitchell, AP
真菌病原体白色念珠菌的氟康唑耐药可以通过几种机制产生，但对负责的基因和途径知之甚少。我们在这里报告的突变CKA 2，通过插入突变筛选确定，赋予氟康唑耐药。CKA 2及其同源物CKA 1指定蛋白激酶CK 2的催化亚基。虽然cka 1突变对氟康唑耐药的影响很小，但CKA 1过表达抑制了cka 2突变体的氟康唑耐药。这一观察结果，沿着合成的cka 1-cka 2相互作用，认为Cka 1 p和Cka 2 p执行类似的功能。cka 2突变体过表达CDR 1和CDR 2，两种氟康唑外排转运蛋白基因，并且CDR 1突变降低cka 2突变体的耐药性，正如预期的，如果CDR 1和CDR 2过表达是cka 2突变体的氟康唑耐药性的原因。蛋白磷酸酶钙调磷酸酶是唑类药物耐受所必需的，我们发现钙调磷酸酶抑制剂环孢菌素可以逆转cka 2突变体的氟康唑耐药性。此外，CRZ 1中的突变，其指定了作为钙调神经磷酸酶的主要靶点的酿酒酵母转录因子的同源物，抑制了cka 2突变体的氟康唑抗性。对Cka 2 p反应基因的表达分析表明，Cka 2 p和Crz 1 p通过不同的机制起作用。几种临床氟康唑耐药菌株过表达一些Cka 2 p反应基因。我们认为，Cka 2 p依赖的调节途径是由临床衍生的唑类耐药突变改变。
Fluconazole resistance of the fungal pathogen Candida albicans can arise through several mechanisms, but the responsible genes and pathways are poorly understood. We report here that mutations in CKA2, identified through an insertional mutagenesis screen, confer fluconazole resistance. CKA2 and its homologue CKA1 specify catalytic subunits of protein kinase CK2. Although cka1 mutations have little effect on fluconazole resistance, CKA1 overexpression suppresses the fluconazole resistance of a cka2 mutant. This observation, along with synthetic cka1-cka2 interactions, argues that Cka1p and Cka2p carry out similar functions. cka2 mutants overexpress CDR1 and CDR2, two fluconazole efflux transporter genes, and a cdr1 mutation decreases resistance of a cka2 mutant, as expected if CDR1 and CDR2 overexpression is responsible for fluconazole resistance of the cka2 mutant. The protein phosphatase calcineurin is required for azole tolerance, and we find that the calcineurin inhibitor cyclosporin reverses fluconazole resistance of cka2 mutants. In addition, a mutation in CRZ1, which specifies a homologue of the Saccharomyces cerevisiae transcription factor that is a major target of calcineurin, suppresses fluconazole resistance of cka2 mutants. Expression analysis of Cka2p-responsive genes argues that Cka2p and Crz1p act through distinct mechanisms. Several clinical fluconazole-resistant isolates overexpress some Cka2p-responsive genes. We suggest that a Cka2p-dependent regulatory pathway is altered by clinically derived azole resistance mutations.