Recombinant expression of tatABC and tatAC results in the formation of interacting cytoplasmic TatA tubes in Escherichia coli.
The twin-arginine translocation (Tat) system of bacteria and plant plastids serves to translocate folded proteins across energized biological membranes. In Escherichia coli, the three components TatA, TatB, and TatC mediate this membrane passage. Here we demonstrate that TatA can assemble to form clusters of tube-like structures in vivo. While the presence of TatC is essential for their formation, TatB is not required. The TatA tubes have uniform outer and inner diameters of about 11.5 nm and 6.7 nm, respectively. They align to form a crystalline-like structure in which each tube is surrounded by six TatA tubes. The tube structures become easily detectable even at only a 15-fold overexpression of the tatABC genes. The TatA tubes could also be visualized by fluorescence when untagged TatA was mixed with low amounts of TatA-GFP. The structures were often found in contact with the cell poles. Because TatC is most likely polar in E. coli, as demonstrated by a RR-dependent targeting of translocation-incompatible Tat substrates to the cell poles, and because TatC is required for the formation of aligned TatA tubes, it is proposed that the TatA tubes are initiated at polarly localized TatC.
Berthelmann
Felix
F
Institute of Biology/Microbiology, Martin Luther University of Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle, Germany.
Mehner
Denise
D
Institute of Biology/Microbiology, Martin Luther University of Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle, Germany.
Richter
Silke
S
Institute of Biology/Microbiology, Martin Luther University of Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle, Germany.
Lindenstrauss
Ute
U
Institute of Biology/Microbiology, Martin Luther University of Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle, Germany.
Lünsdorf
Heinrich
H
Division of Vaccinology, Helmholtz-Centre for Infection Research, Inhoffenstr. 7, D-38124 Braunschweig, Germany.
Hause
Gerd
G
Biocenter, Martin Luther University of Halle-Wittenberg, Weinbergweg 22, D-06120 Halle, Germany.
Brüser
Thomas
T
Institute of Biology/Microbiology, Martin Luther University of Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06120 Halle, Germany. Electronic address: t.brueser@mikrobiologie.uni-halle.de.
D001671:Biochemistry / Q000379:methods; D003593:Cytoplasm / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000096:biosynthesis*; D018613:Microscopy, Confocal; D008854:Microscopy, Electron; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D017354:Point Mutation; D011994:Recombinant Proteins / Q000737:chemistry*
D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; D011994:Recombinant Proteins; C499697:TatA protein, E coli; C473116:TatB protein, E coli; C461379:TatC protein, E coli; D049452:Green Fluorescent Proteins