Isotation and characterisation of dral, a type II restriction endonuclease recognisting a aequence containing only A:T basepairs, and inhibition of its activity by uv irradiation of substrate DNA

Abstract

A type II restriction endonucleasc, DraI, isolated from Deinococcus radiophilus ATCC 27603 recognises the palindromic hexanucleotide sequence5'-T-T-T-↓A-A-A-3'. 3'-A-A-A-↑T-T-T-5'. and cleaves it, as indicated by the arrows, to produce blunt-ended fragments. The yield of enzyme is 100 to 1000 times that of the only other known type II restriction endonuclease that recognises a sequence composed solely of A:T basepairs, the isoschizomer Ahalll (1). Ultraviolet irradiation of the DNA substrate at relatively low doses inhibits the activity of Dral by "protecting" the recognition sequence and this may be exploited to give control of partial digestion of DNA by DraI. © 1983 IRL Press Limited.