Nucleosome assembly in mammalian cell extracts before and after DNA replication.

摘要: Protein-free DNA in a cytosolic extract supplemented with SV40 large T-antigen (T-Ag), is assembled into chromatin structure when nuclear added. This assembly was monitored by topoisomer formation, micrococcal nuclease digestion and psoralen crosslinking of the DNA. Plasmids containing sequences (ori- ori+) were similar efficiencies whether T-Ag present or not. Approximately 50-80% number nucleosomes vivo could be vitro; however, kinetics differed on replicated unreplicated molecules. In replicative intermediates, observed both pre-replicated post-replicated portions. We conclude that extent nucleosome mammalian cell extracts not dependent upon replication, contrast to previous suggestions. However, highly sensitive assay revealed replication appears facilitate precise folding nucleosome.