Figure 1.

Design of the system. (Step 1) Synthesis of components. Cells deleted for the thioredoxin gene (ΔtrxA) and containing a phagemid conferring Cm^R were used. After infection by helper phage, the phage components necessary for assembly accumulate, but very few particles are made. (Step 2) Permeabilization. Cells were permeabilized in the presence of thioredoxin by one of three methods and incubated to allow particle production. (Step 3) Detection of product. An appropriate amount of the reaction supernatant was added to Tet^R recipient cells carrying the rep mutation (to prevent propagation of helper phage), and the mixture was spread on plates containing tetracycline and chloramphenicol. Transducing particles were scored as the number of Cm^R Tet^R colonies. The arrows indicate incubation periods.