Plasmid P1 replication: negative control by repeated DNA sequences.
AUTOR(ES)
Chattoraj, D
RESUMO
The incompatibility locus, incA, of the unit-copy plasmid P1 is contained within a fragment that is essentially a set of nine 19-base-pair repeats. One or more copies of the fragment destabilizes the plasmid when present in trans. Here we show that extra copies of incA interfere with plasmid DNA replication and that a deletion of most of incA increases plasmid copy number. Thus, incA is not essential for replication but is required for its control. When cloned in a high-copy-number vector, pieces of the incA fragment that each contain only three repeats destabilize P1 plasmids efficiently. This result makes it unlikely that incA specifies a regulatory product. Our in vivo results suggest that the repeating DNA sequence itself negatively controls replication by titrating a P1-determined protein, RepA, that is essential for replication. Consistent with this hypothesis is the observation that the RepA protein binds to the incA fragment in vitro.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=391943Documentos Relacionados
- P1 plasmid replication: initiator sequestration is inadequate to explain control by initiator-binding sites.
- P1 plasmid replication: measurement of initiator protein concentration in vivo.
- Antiparallel plasmid-plasmid pairing may control P1 plasmid replication.
- Evidence for positive regulation of plasmid prophage P1 replication: integrative suppression by copy mutants.
- P1 plasmid replication requires methylated DNA.