Mechanism of recruitment of DnaB helicase to the replication origin of the plasmid pSC101
AUTOR(ES)
Datta, Hirock J.
FONTE
The National Academy of Sciences
RESUMO
Although many bacterial chromosomes require only one replication initiator protein, e.g., DnaA, most plasmid replicons depend on dual initiators: host-encoded DnaA and plasmid-encoded Rep initiator protein for replication initiation. Using the plasmid pSC101 as a model system, this work investigates the biological rationale for the requirement for dual initiators and shows that the plasmid-encoded RepA specifically interacts with the replicative helicase DnaB. Mutations in DnaB or RepA that disrupt RepA–DnaB interaction cause failure to load DnaB to the plasmid ori in vitro and to replicate the plasmid in vivo. Although, interaction of DnaA with DnaB could not substitute for RepA–DnaB interaction for helicase loading, DnaA along with integration host factor, DnaC, and RepA was essential for helicase loading. Therefore, DnaA is indirectly needed for helicase loading. Instead of a common surface of interaction with initiator proteins, interestingly, DnaB helicase appears to have at least a limited number of nonoverlapping surfaces, each of which interacts specifically with a different initiator protein.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=15095Documentos Relacionados
- Revised Interpretation of the Origin of the pSC101 Plasmid
- The pSC101 par locus alters protein-DNA interactions in vivo at the plasmid replication origin.
- Replication origin mutations affecting binding of pSC101 plasmid-encoded Rep initiator protein.
- Effects of the pSC101 partition (par) locus on in vivo DNA supercoiling near the plasmid replication origin.
- Minimal essential origin of plasmid pSC101 replication: requirement of a region downstream of iterons.