Biochemical and functional characterization of a meiosis-specific Pch2/ORC AAA+ assembly

• DOI: 10.26508/lsa.201900630
• Publication Date: 2020-08-21T20:05:16Z
• Authors: María Ascensión V...; Richard Cardoso d...; Magdalena Firlej; Dongqing Pan; Elisabeth Weir; Annika Sarembe; Vivek B Raina; Tanja Bange; John R Weir; Gerben Vader
• Keywords: DNA Replication; 0303 health sciences; Saccharomyces cerevisiae Proteins; Cell Cycle; DNA Helicases; Origin Recognition Complex; Nuclear Proteins; Cell Cycle Proteins; Replication Origin; Saccharomyces cerevisiae; Prophase; G2 Phase Cell Cycle Checkpoints; Meiosis; 03 medical and health sciences; Saccharomycetales; Research Articles; Protein Binding

Pch2 is a meiosis-specific AAA+ protein that controls several important chromosomal processes. We previously demonstrated that Orc1, a subunit of the ORC, functionally interacts with budding yeast Pch2. The ORC (Orc1-6) AAA+ complex loads the AAA+ MCM helicase to origins of replication, but whether and how ORC collaborates with Pch2 remains unclear. Here, we show that a Pch2 hexamer directly associates with ORC during the meiotic G2/prophase. Biochemical analysis suggests that Pch2 uses its non-enzymatic NH2-terminal domain and AAA+ core and likely engages the interface of ORC that also binds to Cdc6, a factor crucial for ORC-MCM binding. Canonical ORC function requires association with origins, but we show here that despite causing efficient removal of Orc1 from origins, nuclear depletion of Orc2 and Orc5 does not trigger Pch2/Orc1-like meiotic phenotypes. This suggests that the function for Orc1/Pch2 in meiosis can be executed without efficient association of ORC with origins of replication. In conclusion, we uncover distinct functionalities for Orc1/ORC that drive the establishment of a non-canonical, meiosis-specific AAA+ assembly with Pch2.