HsOrc4-dependent DNA remodeling of the ori-β DHFR replicator

Abstract

Replication of DNA in multicellular organisms initiates from origin of replication (ori) sequences, which significantly differ in length and complexity. One of the best characterized is hamster dihydrofolate reductase (DHFR), which contains the ori-β sequence with several functionally relevant domains, such as an AT-rich region, dinucleotide repeat element (DNR), sequence-induced bend DNA (BEND) and a RIP60 protein-binding site (RIP60). Prior to initiation, ori sequences are recognized by origin recognition complex (ORC), which is a hetero hexamer complex that serves as the landing pad for proteins of the pre-replication complex. The function of each ORC subunit is still unclear. In this study, we analyze the function of subunit 4 of the human ORC complex (HsOrc4) in interaction with a plasmid bearing the ori-β DHFR sequence. We show that the topologically closed DHFR ori-β replicator contains a bubble-like structure within its AT-rich region and that it is reversibly modified in the interaction with HsOrc4. The non-canonical structure of the AT-rich region in the topologically closed ori sequence is recognized and changed by HsOrc4 using the energy of supercoiled DNA. These findings could help to further elucidate DNA replication and its possible association with human genetic diseases.

The landscape of the long non-coding RNAs and circular RNAs of the abdominal fat tissues in the chicken lines divergently selected for fatness

“…Besides, the genes involved in the cellular cycle ( ORC4 and WEE1 gene) were identified to co-express with the corresponding lncRNAs. OCR4 is one of the six subunits of the origin recognition complex (OCR), responsible for DNA replication by remodeling the structure of the origin of replication in humans [ 49 ]. The tumor suppressor, WEE1 regulates the replication forks and genome stability, inhibiting the replication of cells with altered DNA in humans [ 50 ].…”