TY - JOUR TI - In vivo experiments do not support the charge zipper model for Tat translocase assembly AU - Alcock, Felicity AU - Damen, Merel PM AU - Levring, Jesper AU - Berks, Ben C A2 - Gilmore, Reid VL - 6 PY - 2017 DA - 2017/08/31 SP - e30127 C1 - eLife 2017;6:e30127 DO - 10.7554/eLife.30127 UR - https://doi.org/10.7554/eLife.30127 AB - The twin-arginine translocase (Tat) transports folded proteins across the bacterial cytoplasmic membrane and the plant thylakoid membrane. The Tat translocation site is formed by substrate-triggered oligomerization of the protein TatA. Walther and co-workers have proposed a structural model for the TatA oligomer in which TatA monomers self-assemble using electrostatic ‘charge zippers’ (Cell (2013) 132: 15945). This model was supported by in vitro analysis of the oligomeric state of TatA variants containing charge-inverting substitutions. Here we have used live cell assays of TatA assembly and function in Escherichia coli to re-assess the roles of the charged residues of TatA. Our results do not support the charge zipper model. Instead, we observe that substitutions of charged residues located in the TatA amphipathic helix lock TatA in an assembled state, suggesting that these charged residues play a critical role in the protein translocation step that follows TatA assembly. KW - membrane protein KW - protein transport KW - Tat system JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -