Expression and proteolytic processing of the darA antirestriction gene product of bacteriophage P1

The darA gene coding for one of the two bacteriophage P1 antirestriction functions is expressed late after infection or induction. The protein is made as a high-molecular-weight soluble precursor. This is proteolytically cleaved to the mature form, which is a structural component of the phage head. Defective mutants of the phage have been found in which the synthesis of gpdarA is normal but processing does not take place. These mutations all map to the same region of the P1 genome and we propose that they lie in the structural gene for the processing protease.