Journal Article

FZJ-2018-02576

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png The early mature part of bacterial twin-arginine translocation (Tat) precursor proteins contributes to TatBC receptor binding

Ulfig, A. ; Freudl, R. (Corresponding author)FZJ*

2018
Soc. Bethesda, Md.

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Please use a persistent id in citations: http://hdl.handle.net/2128/22659  doi:10.1074/jbc.RA118.002576

Abstract: The twin-arginine translocation (Tat) pathway transports folded proteins across bacterial membranes. Tat precursor proteins possess a conserved twin-arginine (RR) motif in their signal peptides that is involved in the binding of the proteins to the membrane-associated TatBC receptor complex. In addition, the hydrophobic region in the Tat signal peptides also contributes to TatBC binding, but whether regions beyond the signal-peptide cleavage site are involved in this process is unknown. Here, we analyzed the contribution of the early mature protein part of the Escherichia coli trimethylamine N-oxide reductase (TorA) to productive TatBC receptor binding. We identified substitutions in the 30 amino acids immediately following the TorA signal peptide (30aa-region) that restored export of a transport-defective TorA[KQ]-30aa-MalE precursor, in which the RR residues had been replaced by a lysine–glutamine pair. Some of these substitutions increased the hydrophobicity of the N-terminal part of the 30aa-region and thereby likely enhanced hydrophobic substrate–receptor interactions within the hydrophobic TatBC substrate-binding cavity. Another class of substitutions increased the positive net charge of the region's C-terminal part, presumably leading to strengthened electrostatic interactions between the mature substrate part and the cytoplasmic TatBC regions. Furthermore, we identified substitutions in the C-terminal domains of TatB following the transmembrane segment that restored transport of various transport-defective TorA–MalE derivatives. Some of these substitutions most likely affected the orientation or conformation of the flexible, carboxy-proximal helices of TatB. Therefore, we propose that a tight accommodation of the folded mature region by TatB contributes to productive binding of Tat substrates to TatBC.

Note: Biotechnologie 1

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Contributing Institute(s):

1. Biotechnologie (IBG-1)

Research Program(s):

1. 581 - Biotechnology (POF3-581) (POF3-581)

Appears in the scientific report 2018

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Database coverage:
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