The BAH domain facilitates the ability of human Orc1 protein to activate replication origins in vivo.
Selection of initiation sites for DNA replication in eukaryotes is determined by the interaction between the origin recognition complex (ORC) and genomic DNA. In mammalian cells, this interaction appears to be regulated by Orc1, the only ORC subunit that contains a bromo-adjacent homology (BAH) domain. Since BAH domains mediate protein-protein interactions, the human Orc1 BAH domain was mutated, and the mutant proteins expressed in human cells to determine their affects on ORC function. The BAH domain was not required for nuclear localization of Orc1, association of Orc1 with other ORC subunits, or selective degradation of Orc1 during S-phase. It did, however, facilitate reassociation of Orc1 with chromosomes during the M to G1-phase transition, and it was required for binding Orc1 to the Epstein-Barr virus oriP and stimulating oriP-dependent plasmid DNA replication. Moreover, the BAH domain affected Orc1's ability to promote binding of Orc2 to chromatin as cells exit mitosis. Thus, the BAH domain in human Orc1 facilitates its ability to activate replication origins in vivo by promoting association of ORC with chromatin.
Noguchi
Kohji
K
National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Vassilev
Alex
A
Ghosh
Soma
S
Yates
John L
JL
DePamphilis
Melvin L
ML
D000595:Amino Acid Sequence; D002453:Cell Cycle; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D017124:Conserved Sequence; D004261:DNA Replication; D004854:Herpesvirus 4, Human; D006801:Humans; D009154:Mutation; D051738:Origin Recognition Complex / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010957:Plasmids; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D018741:Replication Origin; D014764:Viral Proteins / Q000235:genetics / Q000502:physiology
D002843:Chromatin; D051738:Origin Recognition Complex; D014764:Viral Proteins