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Disruption of the nucleosomes at the replication fork.
Author(s) -
Gruss C.,
Wu J.,
Koller T.,
Sogo J.M.
Publication year - 1993
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1002/j.1460-2075.1993.tb06142.x
Subject(s) - library science , biology , computer science
The fate of parental nucleosomes during chromatin replication was studied in vitro using in vitro assembled chromatin containing the whole SV40 genome as well as salt‐treated and native SV40 minichromosomes. In vitro assembled minichromosomes were able to replicate efficiently in vitro, when the DNA was preincubated with T‐antigen, a cytosolic S100 extract and three deoxynucleoside triphosphates prior to chromatin assembly, indicating that the origin has to be free of nucleosomes for replication initiation. The chromatin structure of the newly synthesized daughter strands in replicating molecules was analysed by psoralen cross‐linking of the DNA and by micrococcal nuclease digestion. A 5‐ and 10‐fold excess of protein‐free competitor DNA present during minichromosome replication traps the segregating histones. In opposition to published data this suggests that the parental histones remain only loosely or not attached to the DNA in the region of the replication fork. Replication in the putative absence of free histones shows that a subnucleosomal particle is randomly assembled on the daughter strands. The data are compatible with the formation of a H3/H4 tetramer complex under these conditions, supporting the notion that under physiological conditions nucleosome core assembly on the newly synthesized daughter strands occurs by the binding of H2A/H2B dimers to a H3/H4 tetramer complex.