Cloning methylated DNA

Wolfgang Schechinger hubahopp at
Wed Nov 3 12:16:22 EST 2004


when you ligate any PCR product (which is always unmethylated) into any
cloning vector, there is a 99.99999% chance that the vector DNA is
methylated as almost all K12 strains will produce methylated DNA. When
these E. coli replicate DNA, the products always will be methylated as
their polyerases will copy the DNA and their methylases will methylate
unmethylated DNA. 

In general, methylation negative strains are only used for special purposes
(see NEB catalogue in the TEch section e.g.).

Best regards,


At 00:47 04.11.2004 +0800, Samantha wrote:
>hi everyone
>my lab mostly use DH5alpha competent cells for transformation. however,
>currently, i want to clone methylated dna. i read papers and most of the
>people use XL1-blue competent cells. I am just wondering if it is possible
>DH5alpha and i guess probably not. Am I right? Thanks!

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