A PERMEABILIZED CELL SYSTEM THAT ASSEMBLES FILAMENTOUS BACTERIOPHAGE

A permeabilized cell system has been developed that is capable of asse mbling filamentous phage only upon addition of exogenous thioredoxin. The in vitro system exhibits the same component requirements seen in v ivo: functional thioredoxin, an intact packaging signal in the substra te DNA, and the assembly protein, pIV. This crude in vitro system is i nsensitive to inhibitors of protein or DNA synthesis, demonstrating th at particle assembly uses components that had accumulated before cell permeabilization. The temporal separation of the synthetic period, dur ing which phage proteins and DNA accumulate, from the assembly period enabled us to examine the energy requirement for assembly. We show her e that ATP hydrolysis is required for filamentous phage assembly and t hat the proton motive force is also important.