S.A. Langeveld

Improved method for the isolation of the A and A* proteins of bacteriophage φX174

The A protein (mol. wt 55 000) encoded by the gene A of bacteriophage φX174 is a multifunctional enzyme that is active in the replication of the viral DNA. This protein initiates a rolling circle type of DNA replication by introducing a break in the viral strand of RF1 DNA at the origin of replication. It is the only phage-coded protein necessary for this type of DNA replication and related phages (e.g., G4) use a similar protein.

VIRAL DNA SEQUENCES AND PROTEINS IMPORTANT IN THE ØX174 DNA SYNTHESIS

ABSTRACT Analysis of recombinant plasmids containing different fragments of the OX174 DNA revealed that a DNA sequence containing the non-coding region between the genes A and H has a function in the in vivo viral DNA synthesis. This sequence, when cloned, interferes with the synthesis of parental RF DNA. The cloned (+) origin interacts in vivo with the A protein of infecting phages, such that a single plasmid DNA strand is packaged into phagecoats. The resulting particle can transform OX-sensitive cells.