FIGURE 3.

Hetero-oligomerization of TatE and TatA. A, INV containing the indicated Tat components were UV-irradiated (+) to initiate cross-linking of the Thr-7Bpa variant of TatE and the Trp-7Bpa variant of TatA. Homo- and hetero-oligomeric TatE adducts were resolved by Tricine SDS-PAGE and detected by immunoblots using anti-TatE (αTatE), anti-TatA (αTatA), anti-TatB (αTatB), and anti-TatC (αTatC) antibodies. Orange stars mark TatE oligomers. The approximately 19-kDa adducts to TatE^Thr-7Bpa (orange dots) and TatA^Trp-7Bpa (magenta dots) are recognized by both antibodies and therefore indicate 1:1 complexes between TatE and TatA. TatE-TatB cross-links are labeled with orange triangles. The αTatC immunoblot confirms equal loads of all vesicles analyzed. Numbers to the left indicate the molecular masses of protein markers in kilodalton. B, as in A, except that INV contained the Bpa variants of TatE and TatA at position Gly-33. TatE^Gly-33Bpa yielded more prominent heterodimers with TatA than homodimers with TatE.