T. Taira et al., AUTONOMOUSLY REPLICATING SEGMENT IDENTIFIED IN THE MURINE P53 GENE CONTAINS P53 RECOGNITION SEQUENCE AND BENDING REGION, International journal of oncology, 7(1), 1995, pp. 115-122
The mouse p53 gene, spreading over 16 kb, was divided into 10 segments
of approximately 1,000 bp and subcloned into pUC19. The clones were t
ransfected into mouse L cells together with an expression vector of th
e hygromycin B- or blasticidin S-resistance gene. The transfected cell
s were cultured in the drug-containing medium to establish cell lines
resistant to the drug. Among the established lines, a high percentage
of the cells originally transfected with pp53(H-R), possessing the Hin
dIII-EcoRI fragment located downstream from the last coding exon of th
e p53 gene, harbored plasmid DNAs in an episomal state. The plasmid DN
As recovered from the 53HR cell-lines, transfected with pp53(H-R), wer
e indistinguishable in structure from the original plasmids used for t
ransfection, as assayed by Southern blotting and back-transformation t
o bacteria. The plasmids in episome of the cells replicated once per c
ell cycle in S phase in concert with chromosomal DNA. In the HindIII-E
coRI fragment (i.e., the p53(H-R) fragment) which showed a highly effi
cient replication activity, there exists a putative sequence for p53 r
ecognition near the HindIII site. A DNA bending region with the cluste
rs of AT tracts also exists near the EcoRI site of the same p53(H-R) f
ragment. In a transient replication system, pp53(H-R) autonomously rep
licated in episome of transfected cells, while mutant plasmids lacking
either the p53 recognition sequence or the bending region did not. Th
e results suggest that the HindIII-EcoRI region downstream from the p5
3 gene contains an activity of cellular DNA replication and both the p
53 recognition sequence and the bending region are necessary for the r
eplication activity.