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Specific telomerase RNA residues distant from the template are essential for telomerase function
J Roy1, T B Fulton, E H Blackburn
1Departments of Microbiology and Immunology and Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California 94143-0414 USA.
Genes & Development
|October 24, 1998
Summary
Investigating non-template regions of telomerase RNA in yeast revealed essential elements for its function. Specific mutations disrupted ribonucleoprotein assembly or enzymatic activity, highlighting critical RNA roles beyond templating.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- Telomerase is a ribonucleoprotein enzyme responsible for maintaining chromosome ends by adding telomeric repeats.
- The telomerase RNA component serves as a template for repeat synthesis, but the function of other RNA regions is less understood, especially in yeast.
- Budding yeast Kluyveromyces lactis provides a model system to study telomerase RNA structure-function relationships.
Purpose of the Study:
- To investigate the functional roles of non-template residues within the telomerase RNA of Kluyveromyces lactis.
- To identify essential regions of the telomerase RNA required for in vivo function, enzymatic activity, and ribonucleoprotein (RNP) assembly.
- To elucidate how specific mutations in these regions impact telomerase complex formation and catalytic function.
Main Methods:
- Systematic mutagenesis of non-template regions in the Kluyveromyces lactis telomerase RNA.
- Analysis of mutant telomerase RNA stability and ribonucleoprotein (RNP) assembly in vivo.
- Assays for in vitro telomerase enzymatic activity and characterization of RNA conformation changes.
Main Results:
- Approximately half of the telomerase RNA residues were dispensable, but four specific regions were essential for in vivo telomerase function.
- Deletion of two essential regions prevented stable RNP assembly, despite RNA synthesis.
- Mutations near the 5' end allowed RNP assembly but abolished enzymatic activity, while mutations in another small region resulted in an inactive RNP with altered RNA conformation.
Conclusions:
- Non-template regions of telomerase RNA play critical roles in both the assembly and catalytic activity of the telomerase ribonucleoprotein complex.
- Specific RNA elements are required for proper RNP formation, while others are crucial for enzymatic function, independent of templating.
- These findings expand our understanding of telomerase RNA's multifaceted roles beyond its templating function.