Retroelement Ty1 Integrase interactome identified using tandem chromatin affinity purification ( TChAP) after in vivo crosslink in yeast Saccharomyces cerevisiae

To identify yeast proteins associated with Ty1 integrase (IN) that could regulate Ty1 replication, we co-purified IN partners using the tandem chromatin affinity purification procedure after in vivo cross-link (TChAP), which we developed previously (Nguyen et al. 2014). We first identified RNA Pol I and Pol III complexes and also a small subset of additional evolutionary conserved complexes, including PAF1 (Polymerase-Associated Factor 1),FACT (FAcilitates Chromatin Transcription), the proteasome and the CK2 kinase. We next confirmed that CK2 interacts with Ty1 integrase in vivo and repress Ty1 retromobility. We showed that Ty1 IN is a substrate of CK2 in vitro and identified 12 phosphorylated residues. In vivo approaches showed that only part of the protein was phosphorylated in the cells and did not demonstrate any direct evidence between Ty1 IN phosphorylation and retromobility inhibition.