A* protein of bacteriophage [phi]X174 carries an oligonucleotide which it can transfer to the 3-OH of a DNA chain

The bacteriophage φX174 gene A encodes two proteins: gene A protein and A* protein. Purified A* protein acts as a single-stranded, DNA-specific endonuclease which remains covalently attached to the 5′-end of the cleavage site. Incubation of A* protein with the synthetic heptamer CAACTTG or with oligonucleotides which yield this heptamer after cleavage with the A* protein yields oligonucleotides with the sequences CAACTTGAG, CAACTTGAGG and CAACTTGAGGA. This indicates that A* protein carries an oligonucleotide with the sequence -AG, AGG or -AGGA. The oligonucleotide can be transferred to the 3′-end of the heptamer CAACTTG. This suggests that A* protein reacts with a specific DNA sequence in the infected cell. Author Keywords: Bacteriophage φX174; A* protein; DNA—protein complex; Synthetic oligonucleotide; DNA-ligating activit