The nucleotide sequence of two restriction fragments located in the gene AB region of bacteriophage S13.

The nucleotide sequence of a double stranded DNA fragment from the gene AB region of bacteriophage S13 DNA has been determined. The fragment was isolated as two adjacent shorter fragments by cleavage of S13 replicative form (RF) DNA with restriction endonuclease III from Hemophilus aegyptius. The strands of the fragments were separated electrophoretically and hydrolyzed with T4 endonuclease IV to yield short oligonucleotides which were then sequenced by partial exonuclease digestion. The complete nucleotide sequence of the restriction fragments was obtained by ordering the inter- and intrastrand overlapping oligonucleotide sequences. The adjacent fragments were 190 nucleotides in length. The sequences included a HindII site, an AluI site and two sequences which may be possible transcription initiation sequences, one with an adjacent sequence homologous to the canonical promoter site sequence T-A-T-Pu-A-T-Pu. Examination of the three possible reading frames for translation of the sequence revealed only one possible complete translation product. The postulated partial sequence of gene A protein has a highly positively charged arginine-rich area which may have importance in DNA binding.