IDENTIFICATION OF A PUTATIVE MITOCHONDRIAL TELOMERE-BINDING PROTEIN OF THE YEAST CANDIDA-PARAPSILOSIS

Terminal segments (telomeres) of linear mitochondrial DNA (mtDNA) mole cules of the yeast Candida parapsilosis consist of large sequence unit s repeated in tandem. The extreme ends of mtDNA terminate with a 5' si ngle-stranded overhang of about 110 nucleotides. We identified and pur ified a mitochondrial telomere-binding protein (mtTBP) that specifical ly recognizes a synthetic oligonucleotide derived from the extreme end of this linear mtDNA. MtTBP is highly resistant to protease and heat treatments, and it protects the telomeric probe hom degradation by var ious DNA-modifying enzymes. Resistance of the complex to bacterial alk aline phosphatase suggests that mtTBP binds the very end of the molecu le. We purified mtTBP to near homogeneity using DNA affinity chromatog raphy based on the telomeric oligonucleotide covalently bound to Sepha rose. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analys is of the purified fractions revealed the presence of a protein with a n apparent molecular mass of similar to 15 kDa. UV cross-linking and g el filtration chromatography experiments suggested that native mtTBP i s probably a homo-oligomer. MtTBP of C. parapsilosis is the first iden tified protein that specifically binds to telomeres of Linear mitochon drial DNA.