A NOVEL GROUP-I INTRON IN CANDIDA-DUBLINIENSIS IS HOMOLOGOUS TO A CANDIDA-ALBICANS INTRON

In the present study, we determined the sequence of group I self-splic ing introns found in the large ribosomal RNA subunit of Candida albica ns, Candida stellatoidea and the recently-described species Candida du bliniensis. It was found that both the intron and ribosomal RNA nucleo tide sequences are almost perfectly identical between different C. alb icans strains as well as between C. albicans and C. stellatoidea strai ns. Comparisons of ribosomal RNA sequences suggest that local isolates of atypical C. albicans from individuals infected with human immunode ficiency virus can be assigned to the C. dubliniensis species. C. dubl iniensis strains also harbor a group I intron in their ribosomal RNA, as observed in about 40% of C. albicans strains and all C. stellatoide a strains. This novel C. dubliniensis group I intron is identical to t he C. albicans and C. stellatoidea intron, except for two widely diver gent stem-loop regions. Despite these differences, the C. dubliniensis intron possesses self-splicing ability in an in vitro assay. Taken to gether, these data support the idea that C. albicans and C. stellatoid ea should be joined together as variants of the same species while C. dubliniensis is a distinct but closely related microorganism. To our k nowledge, the C. albicans and C. dubliniensis introns are the first ex ample of a pair of homologous group I introns differing only by the pr esence of apparently facultative sequences in some stem-loops suspecte d to be involved in stabilization of tertiary structure.