DNA transformation can be difficult to achieve in many bacterial strains due to the presence of one or more restriction and modification (R-M) systems that cleave unmodified DNA that is recognized as "foreign." TypeOne™ Restriction Inhibitor* provides a powerful method for increasing transformation efficiencies in bacterial strains with type I R-M systems. Developed as a unique preparation of a phage protein called ocr,1 TypeOne Inhibitor is readily electroporated into cells along with transforming DNA. In vivo, the protein acts as a molecular decoy that blocks the DNA-binding site of type I R-M enzymes and inhibits DNA cleavage.
Table 1. Effect of TypeOne™ Restriction Inhibitor on transformation efficiencies.
Strain (Type I R-M system)
|Type of DNA or Transposome™||Recombinants |
per µg DNA
|S. typhimurium LT2 (StyL TIII)||pUC19 (100 pg)||3.0 × 106|
|S. typhimurium LT2 (StyL TIII)||X||pUC19 (100 pg)||3.0 × 108|
|E. coli MG1655 (EcoK1)||48 kb fosmid (50 ng)||3.0 × 103|
|E. coli MG1655 (EcoK1)||X||48 kb fosmid (50 ng)||1.4 × 106|
|S. typhimurium LT2 (StyL TIII)||EZ-Tn5™ <R6Kγori/KAN-2>Tnp Transposome™ (1 µl)||1.3 × 104|
|S. typhimurium LT2 (StyL TIII)||X||EZ-Tn5™ <R6Kγori/KAN-2>Tnp Transposome™ (1 µl)||1.0 × 106|