Search PubMedSearch

PubMed · 3540190

Incompatibility between E colicin plasmids.

Abstract

We have tested the ability of pairs of colicin E plasmids to replicate stably in the same cell line. Although many of the pairs of E colicin plasmids were compatible, plasmids ColE3-CA38, ColE7-K317 and ColE8-J were mutually incompatible, as were ColE5-099, ColE6-CT14 and ColE9-J. Incompatibility between ColE6-CT14 and ColE5-099 or ColE9-J was asymmetrical, whereas incompatibility between the other plasmid pairs was symmetrical.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

P C Cooper, F K Hawkins, R James. 1986. Incompatibility between E colicin plasmids.. https://doi.org/10.1099/00221287-132-7-1859

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Enhanced deletion formation by aberrant DNA replication in Escherichia coli.

Repeated genes and sequences are prone to genetic rearrangements including deletions. We have investigated deletion formation in Escherichia coli strains mutant for various replication functions. Deletion was selected between 787 base pair tandem repeats carried either on a ColE1-derived plasmid or on the E. coli chromosome. Only mutations in functions associated with DNA Polymerase III elevated deletion rates in our assays. Especially large increases were observed in strains mutant in dnaQ the epsilon editing subunit of Pol III, and dnaB, the replication fork helicase. Mutations in several other functions also altered deletion formation: the alpha polymerase (dnal;), the gamma clamp loader complex (holC, dnaX), and the beta clamp (dnaN) subunits of Pol III and the primosomal proteins, dnaC and priA. Aberrant replication stimulated deletions through several pathways. Whereas the elevation in dnaB strains was mostly recA- and lexA-dependent, that in dnaQ strains was mostly recA- and lexA-independent. Deletion product analysis suggested that slipped mispairing, producing monomeric replicon products, may be preferentially increased in a dnaQ mutant and sister-strand exchange, producing dimeric replicon products, may be elevated in dnaE mutants. We conclude that aberrant Polymerase III replication can stimulate deletion events through several mechanisms of deletion and via both recA-dependent and independent pathways.

Bacteriocin Plasmids

Colicins B and Ia as novel counterselective agents in interspecies conjugal DNA transfers from colicin-sensitive Escherichia coli donors to other gram-negative recipient species.

Colicins are powerful counterselective agents in conjugal DNA transfers using colicin-sensitive Escherichia coli donor strains and colicin-resistant recipient species. We have constructed a high-level constitutive expression system for the bacteriocin and immunity genes of channel-forming colicins B and Ia to optimize production of these colicins as molecular biology reagents.

Bacteriocin Plasmids

The ColE1 unidirectional origin acts as a polar replication fork pausing site.

Co-orientation of replication origins is the most common organization found in nature for multimeric plasmids. Streptococcus pyogenes broad-host-range plasmid pSM19035 and Escherichia coli pPI21 are among the exceptions. pPI21, which is a derivative of pSM19035 and pBR322, has two long inverted repeats, each one containing a potentially active ColE1 unidirectional origin. Analysis of pPI21 replication intermediates (RIs) by two-dimensional agarose gel electrophoresis and electron microscopy revealed the accumulation of a specific RI containing a single internal bubble. The data obtained demonstrated that initiation of DNA replication occurred at a single origin in pPI21. Progression of the replicating fork initiated at either of the two potential origins was transiently stalled at the other inversely oriented silent ColE1 origin of the plasmid. The accumulated RIs, containing an internal bubble, occurred as a series of stereoisomers with different numbers of knots in their replicated portion. These observations provide one of the first functional explanations for the disadvantage of head-to-head plasmid multimers with respect to head-to-tail ones.

Bacteriocin Plasmids