Rif1 regulates telomere length through conserved HEAT repeats

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Rif1 protein is known to negatively regulate telomere length in budding yeast.
• The precise mechanism and functional domains of Rif1 in telomere length regulation remain unclear.
• Previous studies identified functional domains but did not link them to telomere length control.

Purpose of the Study:

• To identify specific domains of the Rif1 protein responsible for telomere length regulation.
• To elucidate the mechanism by which Rif1 controls telomere length.

Main Methods:

• Tethering Rif1 truncations to a single telomere in budding yeast.
• Measuring the length of the tethered telomere in comparison to bulk telomeres.
• Site-directed mutagenesis of conserved residues within the Rif1 protein.

Main Results:

• A N-terminal domain (Rif1436-577) containing HEAT repeats was sufficient for telomere length regulation when tethered.
• Mutations in charged residues within this region disrupted telomere length regulation.
• Mutations in other conserved residues (436-577) also impaired telomere length maintenance, suggesting a role beyond DNA binding.

Conclusions:

• The N-terminal HEAT repeats domain of Rif1 is critical for telomere length regulation.
• Conserved amino acids in the Rif1436-577 region play a functional role in telomere length control, potentially independent of DNA binding.
• The Rif1 HEAT repeats region may act as a protein-protein interaction interface mediating telomere length regulation.