Interference footprinting analysis of telomerase elongation complexes

Area of Science:

• Biochemistry
• Molecular Biology
• Genetics

Background:

• Telomerase is a crucial enzyme responsible for maintaining telomere length in eukaryotic chromosomes.
• It functions as a reverse transcriptase, synthesizing DNA from an RNA template.
• Understanding telomerase-enzyme interactions is key to comprehending genome stability and aging.

Purpose of the Study:

• To investigate the molecular interactions between Tetrahymena telomerase and its oligonucleotide primers during the elongation reaction.
• To identify and characterize the regions of the telomerase complex involved in primer binding and extension.
• To elucidate the dynamic movement of telomerase components during telomere synthesis.

Main Methods:

• Interference footprinting analysis using base-specific chemical reagents to modify primers.
• Primer extension assays with radiolabeled nucleotides to detect interference.
• Mapping of modified bases to identify functional interaction sites on the telomerase complex.
• Utilizing mutant primers to further probe telomerase-DNA interactions.

Main Results:

• Major functional interactions were identified between telomerase and the 3'-terminal 6-7 residues of primers.
• These interactions involve both the telomerase RNA template and a distinct region, the telomerase DNA interacting surface (TDIS).
• Footprinting analysis revealed that TDIS moves in coordination with the primer's 3' end relative to the template during elongation.

Conclusions:

• Telomerase utilizes a multi-component interaction surface, including TDIS, for primer binding and extension.
• The coordinated movement of TDIS with the primer 3' end is essential for processive telomere elongation.
• This study reveals a novel mechanism of enzyme-substrate interaction in telomere maintenance.