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Updated: Aug 13, 2026

Constructing Mutants in Serotype 1 Streptococcus pneumoniae strain 519/43
Published on: September 11, 2020
Electrotransformation of Streptococcus pneumoniae: evidence for restriction of the DNA on entry
J LeFrançois1, A M Gasc, M Sicard
1Laboratoire de Microbiologie et Génétique Moléculaire du C.N.R.S., Toulouse, France.
Abstract:
Electrotransformation is a method generally used in biotechnology to introduce recombinant DNA into a wide range of bacteria. However the mechanism of DNA entry is poorly understood. We report that in Streptococcus pneumoniae, a naturally transformable species, electrotransformation efficiently introduces a plasmid replicon. DNA is strongly restricted by the restriction-modification systems DpnI and DpnII which degrade methylated and nonmethylated DNA respectively at GATC sequences. This suggests that in electrotransformation double-strand DNA penetrates into these bacteria without a single-strand step in contrast to natural transformation. Single-strand DNA by itself is able to electrotransform very weakly and linearized double-stranded plasmid DNA yields barely detectable levels of transformants.
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