Abstract
The telomerase RNA in yeasts is large, usually >1000 nt, and contains functional elements that have been extensively studied experimentally in several disparate species. Nevertheless, they are very difficult to detect by homology-based methods and so far have escaped annotation in the majority of the genomes of Saccharomycotina. This is a consequence of sequences that evolve rapidly at nucleotide level, are subject to large variations in size, and are highly plastic with respect to their secondary structures. Here, we report on a survey that was aimed at closing this gap in RNA annotation. Despite considerable efforts and the combination of a variety of different methods, it was only partially successful. While 27 new telomerase RNAs were identified, we had to restrict our efforts to the subgroup Saccharomycetacea because even this narrow subgroup was diverse enough to require different search models for different phylogenetic subgroups. More distant branches of the Saccharomycotina remain without annotated telomerase RNA.
Highlights
The linear chromosomes of eukaryotes require a specialized mechanism for completing duplication.Most commonly this is achieved by a special reverse transcriptase, telomerase, that carries a specificRNA that includes the template with telomeric sequence [1]
Annotated protein sequences for 72 yeast species were downloaded from the National Center for Biotechnology Information (NCBI) refseq database
The phylogenetic trees obtained of our phylogenomic analysis of the Saccharomycetales is essentially congruent with the one reported by Shen et al [44]
Summary
The linear chromosomes of eukaryotes require a specialized mechanism for completing duplication.Most commonly this is achieved by a special reverse transcriptase, telomerase, that carries a specificRNA that includes the template with telomeric sequence [1]. The linear chromosomes of eukaryotes require a specialized mechanism for completing duplication. Most commonly this is achieved by a special reverse transcriptase, telomerase, that carries a specific. RNA that includes the template with telomeric sequence [1]. Most likely, this constitutes the ancestral state in eukaryotes. Telomerase has been lost several times in both animals (in particular insects) and possibly in some plants [2]. Genes 2018, 9, 372 structure has been replaced by tandem arrays of DNA sequences that look much like heterochromatin and can be elongated by gene conversion. Specialized telomere-specific retrotransposons are at work in Drosophila [3]
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