FIGURE 5.

Cross-linking of an RR precursor to the transmembrane helix of TatA occurs with faster kinetics than accumulation of translocated material. pSufI was synthesized in the absence or presence of the indicated INV. UV irradiation yielding the pSufI-TatA cross-link (triangle) was started at the indicated times following the addition of INV. The appearance of the signal sequence-less mSufI by the INV-associated signal peptidase indicates the time-dependent translocation into the vesicles. For most of the assays shown, TatA(Bpa)L10 INV had been prepared from cells grown on Bpa (+ Bpa). Cells grown in the absence of Bpa (-Bpa) could not suppress the stop codon at position Leu-10 of TatA. INV derived from these cells therefore failed to cross-link to pSufI.