TatE as a Regular Constituent of Bacterial Twin-arginine Protein Translocases.
Twin-arginine translocation (Tat) systems mediate the transmembrane translocation of completely folded proteins that possess a conserved twin-arginine (RR) motif in their signal sequences. Many Tat systems consist of three essential membrane components named TatA, TatB, and TatC. It is not understood why some bacteria, in addition, constitutively express a functional paralog of TatA called TatE. Here we show, in live Escherichia coli cells, that, upon expression of a Tat substrate protein, fluorescently labeled TatE-GFP relocates from a rather uniform distribution in the plasma membrane into a number of discrete clusters. Clustering strictly required an intact RR signal peptide and the presence of the TatABC subunits, suggesting that TatE-GFP associates with functional Tat translocases. In support of this notion, site-specific photo cross-linking revealed interactions of TatE with TatA, TatB, and TatC. The same approach also disclosed a pronounced tendency of TatE and TatA to hetero-oligomerize. Under in vitro conditions, we found that TatE replaces TatA inefficiently. Our collective results are consistent with TatE being a regular constituent of the Tat translocase in E. coli.
From the Institute of Biochemistry and Molecular Biology, Faculty of Biology, and.
Ekaterina
E
Eimer
From the Institute of Biochemistry and Molecular Biology.
Julia
J
Fröbel
From the Institute of Biochemistry and Molecular Biology, Faculty of Biology, and Spemann Graduate School of Biology and Medicine, University of Freiburg, 79104 Freiburg, Germany.
Anne-Sophie
AS
Blümmel
From the Institute of Biochemistry and Molecular Biology, matthias.mueller@biochemie.uni-freiburg.de.
Matthias
M
Müller
D020816:Amino Acid Motifs; D001120:Arginine / Q000737:chemistry; D002462:Cell Membrane / Q000378:metabolism; D003432:Cross-Linking Reagents / Q000737:chemistry; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D015971:Gene Expression Regulation, Enzymologic; D049452:Green Fluorescent Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding; D021382:Protein Sorting Signals; D021381:Protein Transport
D003432:Cross-Linking Reagents; D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D021382:Protein Sorting Signals; C499697:TatA protein, E coli; C473116:TatB protein, E coli; C461379:TatC protein, E coli; C467897:TatE protein, E coli; D049452:Green Fluorescent Proteins; D001120:Arginine
Escherichia coli (E. coli); membrane transport; protein cross-linking; protein translocation; transport; twin-arginine translocation