白念珠菌ERG11基因启动子部分序列分析

Analysis on Partial Sequence of ERG11 Promoter Region of Candida albicans

目的探讨白念珠菌菌丝相与酵母相ERG11基因启动子部分(-440～-1)碱基序列的差异以及ERG11基因启动子突变与白念珠菌对氟康唑敏感性的关系。方法分别提取从同一亲本来源、对氟康唑敏感性不同的白念珠菌菌丝相与酵母相基因组DNA,根据ERG11基因启动子序列及其编码序列设计一对引物,对ERG11基因上游启动子部分碱基序列(-503～53)进行PCR扩增,经PCR产物直接测序比较白念珠菌菌丝相与酵母相ERG11基因启动子序列(-440～-1)的差异以及对氟康唑敏感性不同的白念珠菌ERG11基因启动子序列的差异。结果白念珠菌菌丝相与酵母相ERG11启动子序列未发现差异。氟康唑敏感株白念珠菌ERG11基因启动子的-365,-353,-328,-310,-308,-299,-295,-293,-292,290,-289位点为杂合状态,且在-284位点有一等位基因发生单碱基缺失(-284delT);而在白念珠菌氟康唑剂量依赖性敏感和耐药株上述杂合现象消失。结论白念珠菌菌丝相与酵母相ERG11基因启动子-440～-1区碱基序列无差异;ERG11基因启动子突变可能与白念珠菌对氟康唑耐药有关。

Objectives To compare the difference of ERG11 partial promoter sequence(-440 ～ -1)between yeast-form and hypha-form of Candida albicans, and the relation between the mutation of ERG11 promoter and the susceptibility of C. albicans to fluconazole. Methods Yeast-form and hypha-form of C. albicans genome DNA were extracted from 4 substrains C. albicans, which were isolated from a single HIV-sero-positive patient. Partial ERG11 promoters of yeast-form and hypha-form of these 4 substrains were amplified by polymerase chain reaction (PCR) and the PCR products were sequenced. Results There was no sequence difference between the yeast-form and the hypha-form of C. albicans in this region. Heterogeneities at position -365, -353, -328, -310, -308, -299, -295, -293, -292, 290, -289 and a single base deletion (-284 delT) were found on one allele of ERG11 promoter region of fluconazole-susceptible substrains. No heterogeneities were observed in dose-dependent fluconazole-susceptible and fluconazole-resistant substrains. Conclusions There is no difference of ERG11 partial promoter sequence between the yeast-form and the hypha-form C. albicans. The mutation of ERG11 promoter may be associated with the resistance of C. albicans to fluconazole.