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

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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.