| Primary Identifier | IPR041664 | Type | Domain |
| Short Name | AAA_16 |
| description | This domain contains a P-loop motif that is characteristic of the AAA superfamily. This domain has been classified as AAA_16 in Pfam and can be found in the Origin Recognition Complex (ORC) subunits and serine/threonine-protein kinase PknK. The Origin Recognition Complex (ORC) is a six-subunit ATP-dependent DNA-binding complex encoded in yeast by ORC1-6 []. ORC is a central component for eukaryotic DNA replication, and binds chromatin at replication origins throughout the cell cycle []. ORC directs DNA replication throughout the genome and is required for its initiation [, , ]. ORC bound at replication origins serves as the foundation for assembly of the pre-replicative complex (pre-RC), which includes Cdc6, Tah11 (akaCdt1), and the Mcm2-7 complex [, , ]. Pre-RC assembly during G1 is required for replication licensing of chromosomes prior to DNA synthesis during S phase [, , ]. Cell cycle-regulated phosphorylation of ORC2, ORC6, Cdc6, and MCM by the cyclin-dependent protein kinase Cdc28 regulates initiation of DNA replication, including blocking reinitiation in G2/M phase [, , , ].Both ORC1 and ORC5 bind ATP, although only ORC1 has ATPase activity []. The binding of ATP by ORC1 is required for ORC binding to DNA and is essential for cell viability []. The ATPase activity of ORC1 is involved in formation of the pre-RC [, , ]. ATP binding by ORC5 is crucial for the stability of ORC as a whole. Only the ORC1-5 subunits are required for origin binding; ORC6 is essential for maintenance of pre-RCs once formed []. Interactions within ORC suggest that ORC2-3-6 may form a core complex []. |
