Yao Y, Enkhtsetseg S, Odsbu I, Fan L, Morigen M. Mutations of DnaA-boxes in the oriR region increase replication frequency of the MiniR1-1 plasmid.
BMC Microbiol 2018;
18:27. [PMID:
29614952 PMCID:
PMC5883639 DOI:
10.1186/s12866-018-1162-3]
[Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 03/02/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND
The MiniR1-1 plasmid is a derivative of the R1 plasmid, a low copy cloning vector.
RESULTS
Nucleotide sequencing analysis shows that the MiniR1-1 plasmid is a 6316 bp circular double-stranded DNA molecule with an oriR1 (origin for replication). The plasmid carries the repA, tap, copA and bla genes, and genes for ORF1 and ORF2. MiniR1-1 contains eight DnaA-binding sites (DnaA-boxes). DnaA-box1 is in the oriR1 region and fully matched to the DnaA-box consensus sequence, and DnaA-box8, with one mismatch, is close to the copA gene. The presence of the MiniR1-1 plasmid leads to an accumulation of the D-period cells and an increase in cell size of slowly growing Escherichia coli cells, suggesting that the presence of MiniR1-1 delays cell division. Mutations in the MiniR1-1 DnaA-box1 and DnaA-box8 significantly increase the copy number of the plasmid and the mutations in DnaA-box1 also affect cell size. It is likely that titration of DnaA to DnaA-boxes negatively controls replication of the MiniR1-1 plasmid and delays cell division. Interestingly, DnaA weakly interacts with the initiator protein RepA in vivo.
CONCLUSION
DnaA regulates the copy number of MiniR1-1 as a negative factor through interacting with the RepA protein.
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