Identification of protein–protein interactions between the TatB and TatC subunits of the twin-arginine translocase system and respiratory enzyme specific chaperones

• Published in: Biochimica et biophysica acta Vol. 1858; no. 4; pp. 767 - 775
• Main Authors: Kuzniatsova, Lalita, Winstone, Tara M.L., Turner, Raymond J.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.04.2016
• Subjects: Carrier Proteins - chemistry; Carrier Proteins - metabolism; Cell Membrane - chemistry; Cell Membrane - metabolism; Chaperones; DmsD; Escherichia coli - chemistry; Escherichia coli - enzymology; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - metabolism; Formate Dehydrogenases - chemistry; Formate Dehydrogenases - metabolism; Membrane Transport Proteins - chemistry; Membrane Transport Proteins - metabolism; Molecular Chaperones - chemistry; Molecular Chaperones - metabolism; molybdoenzymes; Protein Folding; Protein Interaction Maps; Protein Structure, Tertiary; Protein–protein interaction; REMP; Tat; Twin arginine translocase; Two-hybrid; RR; TMAO; DMSO; DTT; Tat; Chaperones; molybdoenzymes; Twin arginine translocase; Protein–protein interaction; Two-hybrid; REMP; BACTH; ITC; Kd; DmsD
• ISSN: 0005-2736; 0006-3002; 1879-2642
• DOI: 10.1016/j.bbamem.2016.01.025

The Twin-arginine translocation (Tat) pathway serves for translocation of fully folded proteins across the cytoplasmic membrane in bacterial and chloroplast thylakoid membranes. The Escherichia coli Tat system consists of three core components: TatA, TatB, and TatC. The TatB and TatC subunits form the receptor complex for Tat dependent proteins. The TatB protein is composed of a single transmembrane helix and cytoplasmic domain. The structure of TatC revealed six transmembrane helices. Redox Enzyme Maturation Proteins (REMPs) are system specific chaperones, which play roles in the maturation of Tat dependent respiratory enzymes. Here we applied the in vivo bacterial two-hybrid technique to investigate interaction of REMPs with the TatBC proteins, finding that all but the formate dehydrogenase REMP dock to TatB or TatC. We focused on the NarJ subfamily, where DmsD – the REMP for dimethyl sulfoxide reductase in E. coli – was previously shown to interact with TatB and TatC. We found that these REMPs interact with TatC cytoplasmic loops 1, 2 and 4, with the exception of NarJ, that only interacts with 1 and 4. An in vitro isothermal titration calorimetry study was applied to confirm the evidence of interactions between TatC fragments and DmsD chaperone. Using a peptide overlapping array, it was shown that the different NarJ subfamily REMPs interact with different regions of the TatB cytoplasmic domains. The results demonstrate a role of REMP chaperones in targeting respiratory enzymes to the Tat system. The data suggests that the different REMPs may have different mechanisms for this task. [Display omitted] •Most system specific chaperones interact with TatB and/or TatC proteins.•Cytoplasmic regions of TatB and TatC proteins interact with the chaperones.•NarJ subfamily of chaperones interacts with different sequences in TatB.