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Plasmid incompatibility: more compatible than previously thought?

Nileena Velappan1, Daniele Sblattero, Leslie Chasteen

  • 1Biosciences Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.

Protein Engineering, Design & Selection : PEDS
|March 3, 2007
PubMed

Insights

Plasmids with identical replication origins can coexist within bacteria, persisting longer than expected. Higher copy number plasmids demonstrate greater persistence, impacting protein engineering by complicating genotype-phenotype correlations.

Area of Science:

  • Molecular Biology
  • Genetics

Background:

  • Plasmids with the same origin of replication are generally considered incompatible.
  • This incompatibility is a key factor in maintaining plasmid stability and genetic control within bacterial populations.

Purpose of the Study:

  • To re-examine the concept of plasmid incompatibility based on plasmid copy number.
  • To investigate the persistence of plasmids with identical origins of replication within bacterial hosts.

Main Methods:

  • Introducing plasmids with the same origin of replication but different antibiotic resistance genes into bacteria.
  • Selecting for resistance to a single antibiotic to monitor the persistence of other resistance markers.
  • Conducting experiments with varying origins of replication to assess the impact of plasmid copy number.

Main Results:

  • Plasmids with identical origins of replication do not rapidly segregate but persist for multiple growth cycles.
  • Persistence is influenced by the specific antibiotic resistance marker selected for.
  • Higher plasmid copy numbers correlate with longer persistence, though significant persistence is observed even with low copy plasmids.

Conclusions:

  • The established notion of strict plasmid incompatibility requires re-evaluation, particularly concerning copy number.
  • The persistence of co-resident plasmids can complicate genotype-phenotype linkage in protein engineering.
  • This finding has implications for experimental design and interpretation in genetic manipulation and protein studies.

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