Histone octamer dissociation is not required for in vitro replication of simian virus 40 minichromosomes

Replication of chromosomal templates requires the passage of the replication machinery through nucleosomally organized DNA. To gain further insights into these processes we have used chromatin that was reconstituted with dimethyl suberimidate-cross-linked histone octamers as template in the SV40 in vitro replication system. By supercoiling analysis we found that crosslinked histone octamers were reconstituted with the same kinetic and efficiency as control octamers. Minichromosomes with cross-linked nucleosomes were completely replicated, although the efficiency of replication was lower compared with control chromatin. Analysis of the chromatin structure of the replicated DNA revealed that the cross-linked octamer is transferred to the daughter strands. Thus, our data imply that histone octamer dissociation is not a prerequisite for the passage of the replication machinery and the transfer of the parental nucleosomes.