Protocol for precision engineering of plant gene loci by homologous recombination cloning in Escherichia coli. Includes: Key steps in the EL250 RED-HR locus rescue and engineering procedure; Primer design and plasmid constructs; AtSTM gap-repair construct; Targeting construct backbone; Preparation of electrocompetent EL250 cells; Transformation of BAC F24o1 and induction of recombinogenic function in EL250; AtSTM locus rescue from BAC F24o1 by gap-repair HR. - [Read Precision Engineering of Plant Gene Loci by Homologous Recombination Cloning in Escherichia Coli]
Electrocompetent bacteria are prepared by growing cultures tomid-log phase, washing the bacteria extensively at low temperature,and then resuspending them in a solution of low ionic strengthcontaining glycerol. DNA is introduced during exposure of thebacteria to a short high-voltage electrical discharge.
This protocol describes the electroporation of the BMH 81-17 mut S strain that is recommended for tranformation of the site directed mutagenesis of dsDNA (See Protocol on Site-Directed Mutagenesis on Double Stranded DNA). BMH 81-17 mut S are a mismatch repair defective (mut S) Escherichia coli strain. The probability that the two mutations will cosegregate during the first round of DNA replication is increased in this strain.