A phylogenetically based secondary structure for the yeast telomerase RNA.
BACKGROUND
Telomerase is a ribonucleoprotein complex whose RNA moiety dictates the addition of specific simple sequences onto chromosomes ends. While relevant for certain human genetic diseases, the contribution of the essential telomerase RNA to RNP assembly still remains unclear. Phylogenetic analyses of vertebrate and ciliate telomerase RNAs revealed conserved elements that potentially organize protein subunits for RNP function. In contrast, the yeast telomerase RNA could not be fitted to any known structural model, and the limited number of known sequences from Saccharomyces species did not permit the prediction of a yeast specific conserved structure.


RESULTS
We cloned and analyzed the complete telomerase RNA loci (TLC1) from all known Saccharomyces species belonging to the "sensu stricto" group. Complementation analyses in S. cerevisiae and end mappings of mature RNAs ensured the relevance of the cloned sequences. By using phylogenetic comparative analysis coupled with in vitro enzymatic probing, we derived a secondary structure prediction of the Saccharomyces cerevisiae TLC1 RNA. This conserved secondary structure prediction includes a central domain that is likely to orchestrate DNA synthesis and at least two accessory domains important for RNA stability and telomerase recruitment. The structure also reveals a potential tertiary interaction between two loops in the central core.


CONCLUSIONS
The predicted secondary structure of the TLC1 RNA of S. cerevisiae reveals a distinct folding pattern featuring well-separated but conserved functional elements. The predicted structure now allows for a detailed and rationally designed study to the structure-function relationships within the telomerase RNP-complex in a genetically tractable system.
Dandjinou
Alain T
AT
Groupe ARN/RNA Group, Department of Microbiology and Infectious Diseases, Faculty of Medicine, Université de Sherbrooke, 3001 12th Avenue N., Sherbrooke, QC J1H 5N4, Canada.
Lévesque
Nancy
N
Larose
Stéphanie
S
Lucier
Jean-François
JF
Abou Elela
Sherif
S
Wellinger
Raymund J
RJ
D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics; D005453:Fluorescence; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017433:Protein Structure, Secondary; D012313:RNA / Q000235:genetics*; D016914:Ribonuclease H / Q000378:metabolism; D012440:Saccharomyces / Q000235:genetics*; D017422:Sequence Analysis, DNA; D019098:Telomerase / Q000235:genetics*
C422952:telomerase RNA; D012313:RNA; D019098:Telomerase; D016914:Ribonuclease H