DNA is a co-factor for its own replication in Xenopus egg extracts.
Soluble Xenopus egg extracts efficiently replicate added plasmids using a physiological mechanism, and thus represent a powerful system to understand vertebrate DNA replication. Surprisingly, DNA replication in this system is highly sensitive to plasmid concentration, being undetectable below ∼10 pM and highly efficient above ∼75 pM. DNA replication at the high plasmid concentration does not require plasmid-plasmid contacts, since replication is not inhibited when plasmids are immobilized in agarose prior to addition of egg extract. The absence of replication at low plasmid concentration is due to a defect in the assembly of pre-replication complexes (pre-RCs). pre-RC assembly requires contact-independent communication between plasmids. Our results show that in Xenopus egg extracts, aggregation of multiple replication forks is not required for efficient replication of plasmid DNA, and they suggest that DNA functions as a co-factor for its own duplication.
Lebofsky
Ronald
R
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA.
van Oijen
Antoine M
AM
Walter
Johannes C
JC
D000818:Animals; D002457:Cell Extracts; D003600:Cytosol / Q000737:chemistry; D004247:DNA / Q000502:physiology*; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism; D009841:Oligonucleotides / Q000737:chemistry; D010063:Ovum / Q000378:metabolism; D010957:Plasmids / Q000096:biosynthesis / Q000502:physiology; D014981:Xenopus; D000099272:Replisomes
D002457:Cell Extracts; D004247:DNA; D004259:DNA-Directed DNA Polymerase; D009097:Multienzyme Complexes; D009841:Oligonucleotides; D000099272:Replisomes