Template boundary definition in Tetrahymena telomerase

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Telomerase is essential for maintaining chromosome ends (telomeres) by synthesizing repetitive DNA sequences.
• The telomerase complex includes telomerase RNA (TERNA) which contains the template for DNA synthesis and telomerase reverse transcriptase (TERT) which is the catalytic subunit.
• Accurate copying of the TERNA template by TERT is critical for telomere length regulation.

Purpose of the Study:

• To identify the specific region of telomerase RNA responsible for defining the 5' template boundary.
• To investigate the role of telomerase reverse transcriptase (TERT) in this boundary definition process.
• To elucidate the mechanism by which the template boundary is established and maintained.

Main Methods:

• Site-directed mutagenesis of telomerase RNA to identify critical regions.
• RNA binding assays to assess the interaction between TERT and TERNA.
• Biochemical experiments to analyze the functional consequences of mutations on telomerase activity.

Main Results:

• A specific region within telomerase RNA was identified as essential for both 5' template boundary definition and high-affinity binding to TERT.
• Mutations in the RNA binding domain of TERT disrupted both template boundary definition and RNA binding.
• The sequence-specific interaction between this TERNA element and the TERT RNA binding domain, rather than active site motifs, was shown to define the template boundary.

Conclusions:

• The 5' template boundary of telomerase RNA is defined by a sequence-specific interaction with the TERT RNA binding domain.
• This interaction is critical for accurate telomere elongation.
• The findings provide new insights into the regulation of telomerase function at the molecular level.