NUCLEOTIDE-SEQUENCE AND REVISED MAP LOCATION OF THE ARN GENE FROM BACTERIOPHAGE-T4

Non-glucosylated (Glu(-)) T-even phage DNAs are restricted by Escheric hia coil RglA and RglB endonucleases with different specificities. Rgl B endonuclease activity is strongly inhibited by anti-restriction endo nuclease (Am) encoded by the bacteriophage T4 genome. The nucleotide s equence of the am gene encoding Am was determined. The product of the cloned am gene was overexpressed by the T7 RNA polymerase/promoter sys tem, and its molecular size is consistent with that predicted from the open reading frame of the arn gene. The arn gene is located between t he asiA gene and motA gene in the region of 161,300-161,578 nucleotide s.