Nucletide sequencing of DNA topoisomerase II gene for diagnosis of fungal infection

我们测定了从致病性念珠菌（C.dubliniensis、C.parapsilosis、C.tropicalis、C.krusei、C.kefyr、C.guilliermondii和C. lusitaniae）中分离的DNA拓扑异构酶II基因约55%区域（约2.3kb）的核苷酸序列。基于DNA拓扑异构酶II基因，研究了包括白色念珠菌和光滑念珠菌在内的9种念珠菌的进化关系。2192 bp的核苷酸序列，覆盖两个催化结构域，ATP酶和切割/重新密封，进行系统发育分析。序列比较和进化分析表明，这里测试的念珠菌物种不是单系的，并且热带念珠菌和近平滑念珠菌物种内的两种菌株过于多样，不可能是单一物种。DNA拓扑异构酶II的功能域之间的分歧是广泛的，这表明念珠菌属物种至少在DNA拓扑异构酶II基因的不同进化路径。序列信息和观察念珠菌DNA拓扑异构酶II的分子进化的种特异性方式将被应用于开发一种方法来鉴定和表征念珠菌属的自然和临床分离株。

We have determined the nucleotide sequences of about 55 % region of DNA topoisomerase II gene (approximately 2.3 kb) isolated from the pathogenic Candida species, C.dubliniensis, C.parapsilosis, C.tropicalis, C.krusei, C.kefyr, C.guilliermondii and C.lusitaniae. Evolutionary relationships among nine Candida species including those of C.albicans and C.glabrata were studied based on the DNA topoisomerase II gene. The nucleotide sequences of 2192 bp, that covered two catalytic domains ; ATPase and cutting/resealing, were subjected for phylogenetic analysis. Sequence comparison and evolutionary analysis have revealed that the Candida species tested here are not monophyletic, and the two strains within the species C.tropicalis and C.parapsilosis are too diverse to be in a single species. Wide variety of the divergence was observed among the functional domains of DNA topoisomerase II, suggesting that Candida species were in the different evolutionary paths at least as regarding DNA topoisomerase II gene. Sequence information and the observation on species-specific manner of molecular evolution of DNA topoisomerase II in Candida will be applied for developing a method of identification and characterization of the Candida species in both natural and clinical isolates.