The specific uptake of cloned Haemophilus DNA

During the process of transformation Haemophilusinfluenzae cells bind its own DNA but little or no foreign DNA. This specificity for recognition of DNA was studied by cloning Haemophilus DNA in E. coli. Haemophilus DNA fragments were cloned using plasmid pBR322 as a vector. The fragment cH7 cloned in pBR322 was found to be homologous to Haemophilus DNA and shown to bind irreversibly to competent Haemophilus cells. The fact that cH7 isolated from E. coli lacks Haemophilus modification leads to the conclusion that modification does not play a role in the uptake mechanism. Uptake specificity is a function of recognition sequences that reside in DNA itself.