The nuclease specificity of the bacteriophage øX174 A protein

Abstract

The A* protein of bacteriophage øX174 is a single-stranded DNA specific nuclease. It can cleave øX viral ss DNA in many different places. The position of these sites have been determined within the known øX174 nucleotide sequence (1). From the sequences at these sites it is clear that the A protein recognizes and cleaves at sites that show only partial homology with the origin of RF DNA replication in the øX DNA. Different parts of the origin sequence can be deduced that function as a signal for recognition and cleavage by the A* protein. We conclude that different parts within the DNA recognition domain of the A* protein are functional in the recognition of the origin sequence in single-stranded DNA. The existence of different DNA recognition domains in the A* protein, and therefore also in the A protein, leads to a model that can explain how the A protein performs its multiple function in the øX174 DNA replication process (2). © 1981 IRL Press Limited.