Transcriptional activator nuclear factor I stimulates the replication of SV40 minichromosomes in vivo and in vitro.
SV40 DNA replication in vivo is greatly stimulated by cis-acting transcriptional elements. We studied a model viral chromosome containing a single binding site for the cellular transcriptional activator, nuclear factor I (NF-I/CTF), located adjacent to the replication origin. The presence of the NF-I recognition site increased replication efficiency over 20-fold in vivo. Purified NF-I had little effect on the replication efficiency in the standard SV40 cell-free system when the template was introduced as naked DNA. However, NF-I specifically prevented the repression of DNA replication that occurred when the template was preassembled into chromatin. Our data support a model in which the binding of a transcriptional activator perturbs the local distribution of nucleosomes, thereby increasing the accessibility of the origin region.
Cheng
L
L
Department of Molecular Biology and Genetics, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
Kelly
T J
TJ
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D004261:DNA Replication; D005809:Genes, Regulator; D005814:Genes, Viral; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010957:Plasmids; D013539:Simian virus 40 / Q000235:genetics*; D013698:Templates, Genetic; D013816:Thermodynamics; D015534:Trans-Activators / Q000302:isolation & purification / Q000378:metabolism*
D002843:Chromatin; D015534:Trans-Activators