EcoRI-sensitive mutation of T7 phage.

It is known that DNA from phage T7 is not cleaved by restriction endonuclease EcoRI. However, DNA from phage T7am28 (gene 5) mutant (Studier, 1969) was found to be cleaved by the endonuclease at one site. The site is located at 0.46 fractional length from the left end of the molecule. The mutation which makes T7 DNA sensitive to the endonuclease is separable from the amber nutation and located between am28 and am233 (gene 6).