GSE184051
Telomerase RNA subunit of Ustilago maydis
The RNA subunit of telomerase is an essential component whose primary sequence and length are poorly conserved among eukaryotic organisms. The phytopathogen Ustilago maydis is a dimorphic fungus of the Ustilaginaceae family. We analyzed several members of the Ustilaginaceae family to computationally identify the TElomere RNA (TER) gene ter114. To confirm the identity of the TER gene, we disrupted the gene and characterized telomerase-negative mutants. Similar to catalytic TERT mutants, ter114? mutants exhibit phenotypes of telomere shortening and low replicative potential. However, ter114? mutants had very prolonged replication times, and survivors arose more rapidly in ter114? (252 replication rounds) than in their counterpart trt1? mutant strains (300 replication rounds). ter114-disrupted mutants were unable to infect maize seedlings in heterozygous crosses and showed defects such as cell cycle arrest and segregation failure. We concluded that ter114, which encodes the TER subunit of the telomerase of U. maydis, could have distinct or more extensive functions than trt1. To further characterize the ter114 gene, we analyze the transcriptomes of both, mRNA nuclear transcripts and nuclear RNA ribo-depleted transcripts of the wild-type strain 521, from the reads of both nuclear fractions, we find four reconstructed transcripts of the ter114 locus, which constitute four isoforms containing the structural domains of TER. The results showed that the transcription start site for the four isoforms is located upstream the start codon of the uncharacterized gene UMAG_03168, while the differential expression analysis showed that the ter114-i4 isoform is up-regulated with respect to the polyadenylated fraction, suggesting that this transcript could correspond to the precursor of the mature form of TER. Overall design: Examination of the expression profiles of the polyA nuclear fraction and the total nuclear fraction in wild-type haploid cells