Nucleic Acids Research, 1994, Vol. 22, No. 24 5265-5270
© 1994
Articles |
Re-replication of SV40 minichromosomes is inhibited at the stage of chain elongation
Fakultat fuÜr Biologie, Universitat Konstanz D-78434 Konstanz, Germany
*To whom correspondence should be addressed
+Present address: Wellcome/CRC Institute, Tennis Court Road, Cambridge CB2 1QR, UK
Received September 12, 1994. Accepted November 8, 1994.
The template activities of protein-free SV40 DNA and SV40 minichromosomes for DNA re-repllcatlon are compared in In vitro replication assays. Density substitution experiments and two-dimensional gel electrophoresis show that protein-free DNA can replicate for at least two cycles whereas salt-treated minichromosomes replicate only once. Re-repllcatlon of minichromosomes is blocked at the stage of replicatlve chain elongation suggesting that repll-catively assembled chromatin has structural features that prevent a second round of replication.