FIGURE 4.

TatE also interacts with TatB. INV were prepared from E. coli strains expressing the Asp-31Bpa variants of TatA and TatE in combination with the indicated Tat components. After UV irradiation, INV were probed for TatA- and TatE-cross-reactive material by immunoblotting using anti-TatE (αTatE), anti-TatA (αTatA), anti-TatB (αTatB), and anti-TatC (αTatC) antibodies. The 38-kDa TatE-TatB complexes are labeled with orange triangles and those between TatA and TatB with magenta triangles. Marked are homo-oligomers of TatA (magenta stars) and TatE (orange stars) and heterodimers formed between TatE and TatA and between TatA and TatE (orange and magenta dots, respectively). The TatA-TatE oligomer of ∼38 kDa (lane 12, αTatA, top magenta dot) is presumably a TatA dimer cross-linked to one TatE molecule and, as such, is not visible in the absence of TatE (lane 10).