Complete DNA sequences of the mitochondrial genomes of the pathogenic yeasts Candida orthopsilosis and C. metapsilosis.
Peter Kosa (1), Matus Valach (1), Lubomir Tomaska (2), Kenneth H. Wolfe (3), Jozef Nosek (1)
(1) Department of Biochemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak republic; (2) Department of Genetics, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak republic; (3) Department of Genetics, University of Dublin, Trinity College, Dublin, Ireland
Two yeast species C. orthopsilosis and C. metapsilosis, originally classified as the groups II and III of the form species C. parapsilosis, were recently established as independent taxa (Tavanti et al. J.Clin.Microbiol. 43 : 284, 2005). To investigate how the speciation shaped their genetic blueprints we determined the complete sequences of the mitochondrial DNA of the C. orthopsilosis MCO456 and the C. metapsilosis MCO448. The comparison with C. parapsilosis (Nosek et al. Mol. Genet. Genom. 272 : 173, 2004) confirmed previous indications (Rycovska et al. Microbiology 150 :1571, 2004) that these mitochondrial genomes contain an identical set of genes organized in the same order. The most significant differences result from the presence/absence of introns and variations in the sequences encoding the ribosomal RNAs. Minor changes were detected within several transfer RNAs and proteins. Importantly, the mitochondrial genomes of C. parapsilosis and C. metapsilosis are represented by linear DNA molecules terminating with arrays of tandem repeats. Their mitochondria contain minicircular molecules derived from the telomeric sequence (t-circles) that are implicated in the mitochondrial telomere maintenance (Nosek et al. J. Biol. Chem. 280 : 10840, 2005). In contrast, C. orthopsilosis MCO456 lacks t-circles and contains a circularized genome formed by intramolecular end-to-end fusion. These results have implications for evolution of the molecular architecture of the organellar genome.