Pch2 Prevents Mec1/Tel1-Mediated Hop1 Phosphorylation Occurring Independently of Red1 in Budding Yeast Meiosis

A prominent feature of meiosis in most sexually reproducing organisms is interhomolog recombination whereby a significant fraction of the programmed meiotic double-strand breaks are repaired using intact homologous non-sister chromatids rather than sister chromatids. Budding yeast DNA damage checkpoint kinases Mec1 and Tel1 act together with the axial element protein Red1 to promote interhomolog recombination by phosphorylating another axial element protein Hop1. Mec1 and Tel1 also phosphorylate γH2A and the synaptonemal complex protein Zip1 independently of Red1 to facilitate premeiotic DNA replication and to destabilize homology-independent centromere pairing, respectively. It has been unclear why Hop1 phosphorylation is Red1-dependent. Here, we report that the pachytene checkpoint protein 2 (Pch2) specifically prevents Red1-independent Hop1 phosphorylation. Our findings reveal a new function for Pch2 in linking two axial element proteins Red1 and Hop1 thus coordinating their effects in meiotic recombination and the checkpoint network.