The Tat system for membrane translocation of folded proteins recruits the membrane-stabilizing Psp machinery in Escherichia coli

authored by

Denise Mehner, Hendrik Osadnik, Heinrich Lünsdorf, Thomas Brüser

Abstract

Tat systems transport folded proteins across energized membranes of bacteria, archaea, and plant plastids. In Escherichia coli, TatBC complexes recognize the transported proteins, and TatA complexes are recruited to facilitate transport. We achieved an abstraction of TatA from membranes without use of detergents and observed a co-purification of PspA, a mem-brane- stress response protein. The N-terminal transmembrane domain of TatA was required for the interaction. Electron microscopy displayed TatA complexes in direct contact with PspA. PspB and PspC were important for the TatA-PspA contact. The activator protein PspF was not involved in the PspATatA interaction, demonstrating that basal levels of PspA already interact with TatA. Elevated TatA levels caused membrane stress that induced a strictly PspBC- and PspF-dependent up-regulation of PspA. TatA complexes were found to destabilize membranes under these conditions. At native TatA levels, PspA deficiency clearly affected anaerobic TMAO respiratory growth, suggesting that energetic costs for transport of large Tat substrates such as TMAO reductase can become growth limiting in the absence of PspA. The physiological role of PspA recruitment to TatA may therefore be the control of membrane stress at active translocons.

Organisation(s)

Institute of Microbiology

External Organisation(s)

Helmholtz Centre for Infection Research (HZI)

Type

Article

Journal

Journal of Biological Chemistry

Volume

287

Pages

27834-27842

No. of pages

9

ISSN

0021-9258

Publication date

10.08.2012

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Biochemistry, Molecular Biology, Cell Biology

Electronic version(s)

https://doi.org/10.1074/jbc.M112.374983 (Access: Open)