Fig. 1

Large-scale purification of Ty1 integrase binding partners. A Ty1 replication cycle. A Ty1 element (grey bar with black triangles at both ends) is transcribed into RNAs that are exported to the cytoplasm and subsequently translated into Gag and Gag-Pol proteins that associate with Ty1 RNA to form Ty1 ribonucleoparticles called retrosomes. The retrosome is the assembly-site for virus-like particles (VLPs) that contains tRNAiMet and a dimer of Ty1 RNA. Within the VLP, Gag and Pol proteins are cleaved by the protease (PR, pink ball) to form mature Gag (blue ball), PR, integrase (IN, orange ball) and reverse transcriptase (RT, purple ball) proteins, and Ty1 RNA is reverse transcribed into cDNA by RT using tRNAiMet as a primer. Then, IN binds to Ty1 cDNA to form the pre-integration complex that contains additional host (yellow and red balls) and retroelement proteins (blue and purple balls) and is imported into the nucleus, where it catalyzes the integration of Ty1 cDNA into the yeast genome. B Functional classification of the Ty1 IN partners based on Gene Ontology (GO) cellular component. GOrilla algorithm [4] was used to retrieve the enriched GO terms within the complete set of proteins identified by TChAP. Only GO hits with an FDR-corrected q-value ≤0.01 were considered statistically significant in the final analysis. Numbers on X-axis indicate the enrichment in each identified GO cluster. Full list of the enriched GO terms is available in Table S3. C CK2 is associated with ectopic IN in vivo. Whole cell extracts from yeast cells expressing WT or TAP-tagged CK2 subunits and expressing or not (−) ectopic IN-HBH from a pTet-off promoter were immunoprecipitated with IgG beads. Proteins were analyzed by Western blot using anti-strep (IN-HBH) or anti-TAP antibodies (CK2). TAP-Tup1 is used as a negative control. Molecular weights are indicated. D Two-hybrid interactions between CK2 subunits and IN. Each CK2 subunit was fused to GAL4 binding domain (GBD) and IN-C-tag to GAL4 activating domain (GAD). GBD or GAD empty vector (−) serves as control. Cells were plated on selective medium and incubated for 2 days. Activation of the LacZ reporter gene was monitored by staining in the presence of X-Gal. E Two-hybrid interaction between GBD-Cka1, −Cka2, −Ckb2 and different IN regions, as depicted on the left panel, fused to GAD. Cells were plated on selective medium and incubated for 2 days. Activation of the LacZ reporter gene was monitored by staining in the presence of X-Gal. The black square corresponds to the bNLS which contains the targeting domain (TD)