Rap1 prevents telomere fusions by nonhomologous end joining

Rap1 prevents telomere fusions by nonhomologous end joining.

Telomeres protect chromosomes from end-to-end fusions. In yeast Saccharomyces cerevisiae, the protein Rap1 directly binds telomeric DNA. Here, we use a new conditional allele of RAP1 and show that Rap1 loss results in frequent fusions between telomeres. Analysis of the fusion point with restriction enzymes indicates that fusions occur between telomeres of near wild-type length. Telomere fusions...

Trapping Rap1 at the telomere to prevent chromosome end fusions.

The prevention of nonhomologous end-joining (NHEJ) reactions between chromosome ends is crucial for maintaining genome stability. Although this protective function is known to be fulfilled by a core of conserved telomeric proteins that are collectively known as Shelterin, its mechanistic details remain a mystery. In this issue, Sarthy et al (2009) lend fresh insight by developing an ingenious m...

A RAP1/TRF2 complex inhibits nonhomologous end-joining at human telomeric DNA ends.

The mechanisms by which telomeres are distinguished from DNA double-strand breaks are poorly understood. Here we have defined the minimal requirements for the protection of telomeric DNA ends from nonhomologous end-joining (NHEJ). Neither long, single-stranded overhangs nor t loop formation is essential to prevent NHEJ-mediated ligation of telomeric ends in vitro. Instead, a tandem array of 12 ...

Bacterial nonhomologous end joining requires teamwork.

All living organisms must repair DNA double-stranded breaks (DSBs) in order to survive. Many bacteria rely on nonhomologous end joining (NHEJ) when only a single copy of the genome is available and maintain NHEJ pathways with a minimum of two proteins. In this issue, Bhattarai and colleagues identify additional factors that can work together to aid in survival of stationary-phase cells with chr...

SnapShot: Nonhomologous DNA End Joining (NHEJ)