Specialized telomeric proteins have an essential role in maintaining genome stability through chromosome end protection and telomere length regulation. In the yeast Saccharomyces cerevisiae, the evolutionary conserved CST complex, composed of the Cdc13, Stn1 and Ten1 proteins, largely contributes to these functions. The team “Recombination and maintenance of genome integrity” has shown, in collaboration with two spanish laboratories (Olga Calvo’s, Salamanca and José Enrique Pérez-Ortín’s, València), that TEN1 exhibited specific genetic interactions with several genes coding for transcription regulators, which was confirmed by molecular assays. Based on data obtained by RNA-seq, ChIP-seq and mass spectrometry, the authors propose that this novel function of CST might serve to stimulate transcription following head-on collisions with an in-coming replication fork.
They speculate that, at the replication fork, Cdc13 and Stn1, which physically associate with Pol1 and Pol12 (Pol a), respectively, perceive a signal emitted by the Mec1, Rad53, Ctf18 and Mrc1 DNA replication checkpoints, which themselves have sensed mechanical vibrations resulting from the clash between the replication fork and the transcription machinery moving in opposite directions. This signal provokes the dissociation between CST and Pol a, allowing the CST complex to attach the promoter of the transcribing gene, via Hmo1, before activating the RNA Pol II machinery, via Spt5.
This study has been published in Nucleic Acids Research (Calvo, Grandin et al. 2019 ).