Identification of the Telomerase RNA in the Filamentous Fungus Aspergillus oryzae

Telomeres are the repetitive sequences located at the ends of linear chromosomes, which protect the DNA from degradation during cellular replication. These structures are elongated by a ribonucleoprotein called telomerase. The protein component of telomerase (TERT) utilizes an RNA template sequence (TR) to reverse transcribe nucleotides onto the 3’ end of the chromosome. While the TERT is highly conserved between organisms, the TR varies greatly in primary sequence and length, thus providing difficulties in identifying the TR of various organisms. We currently know only 3 groups of TRs from ciliates, humans, and yeast. I am interested in identifying the TR sequence in a filamentous fungus, Aspergillus oryzae, which I hypothesize uses a telomerase-based system to maintain the telomeres. Genomic searches for a sequence complementary to the 12 bp telomeric sequence produced 24 candidate TR sequences. I tested 5 sequences for its presence in the RNA by method of RT-PCR. Four of these sequences either did not produced a band for an A. oryzae RNA sample or for a DNA sample. However, 1 sequence did amplify an RNA segment, which indicates that it is transcribed. Additionally, this candidate template sequence follows the other criteria I determined important for the TR sequence. The identification of this filamentous fungus’ telomerase RNA sequence can be further utilized in understanding the telomere length regulation