TatBC-Independent TatA/Tat substrate interactions contribute to transport efficiency

authored by: Johannes Taubert, Bo Hou, H. Jelger Risselada, Denise Mehner, Heinrich Lünsdorf, Helmut Grubmüller, Thomas Brüser
Abstract: The Tat system can transport folded, signal peptide-containing proteins (Tat substrates) across energized membranes of prokaryotes and plant plastids. A twin-arginine motif in the signal peptide of Tat substrates is recognized by TatC-containing complexes, and TatA permits the membrane passage. Often, as in the model Tat systems of Escherichia coli and plant plastids, a third component - TatB - is involved that resembles TatA but has a higher affinity to TatC. It is not known why most TatA dissociates from TatBC complexes in vivo and distributes more evenly in the membrane. Here we show a TatBC-independent substrate- binding to TatA from Escherichia coli, and we provide evidence that this binding enhances Tat transport. First hints came from in vivo cross-linking data, which could be confirmed by affinity co-purification of TatA with the natural Tat substrates HiPIP and NrfC. Two positions on the surface of HiPIP could be identified that are important for the TatA interaction and transport efficiency, indicating physiological relevance of the interaction. Distributed TatA thus may serve to accompany membrane-interacting Tat substrates to the few TatBC spots in the cells.
Organisation(s): Institute of Microbiology
External Organisation(s): Max Planck Institute for Biophysical Chemistry (Karl Friedrich Bonhoeffer Institute)
Helmholtz Centre for Infection Research (HZI)
Type: Article
Journal: PLOS ONE
Volume: 10
ISSN: 1932-6203
Publication date: 16.03.2015
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: General Biochemistry,Genetics and Molecular Biology, General Agricultural and Biological Sciences, General
Electronic version(s): https://doi.org/10.1371/journal.pone.0119761 (Access: Open)