The location of the restriction locus for λ·K in Escherichia coli B

Abstract

Analysis of recombinants from E. coli K 12 Hfr × E. coli B F− crosses showed that one locus on the chromosome of Escherichia coli, controlling restriction and probably also the modification of phage λ, is located between the leading point of the Hfr H chromosome and the locus for threonine synthesis.

The restriction locus also controls the restruction of the fertility factor of K 12 and the restriction of chromosomal DNA of K 12 in E. coli B.

The presence of the defective prophaga X in E. coli B causes an additional restriction for phage λ and for the fertility factor.