Nucleic Acids Research, 1983, Vol. 11, No. 14 4793-4807
© 1983
MOLECULAR BIOLOGY |
Identification of proteins interacting with newly replicated DNA in SV40-infected cells by UV-indnced DNA-protein cross-linking
Department of Biochemistry, Cancer Institute, Okayama University Medical School 251 Shikatacho, Okayama 700, Japan
Received April 11, 1983. Accepted June 20, 1983.
Protein species interacting with newly replicated DNA were analyzed using a photo cross-linking technique. Nascent DNA was labeled in vitro with [
-32 P]dCTP and BrdUTP in SV40-infected CV-1 cells made permeable with saponin. The labeled cells were then irradiated with UV light (254 nm) and were treated extensively with DNase I. Proteins with radioactive DNA tags were separated by SDS-PAGE and visualized by autoradiography. Among 1015 proteins which were cross-linked, the proteins with apparent molecular weights of 16.5 K, 44 K, 82 K and those in the 94140 K region appeared to be associated with newly replicated SV40 DNA. A pulse-chase experiment showed that the 82 K and 94140 K proteins interacted with new DNA in a relatively localized region close to the replication fork. The 44 K protein was identified as the major viral capsid protein, VP1, using antiserum to SV40 capsid proteins. It was suggested that VP1 binds to nascent DNA shortly after DNA synthesis and migrates into chromatin maturation regions.
*Present address: Department of Biochemistry, Osaka University Medical School, Kitaku, Osaka 530, Japan