The TatAd component of the Bacillus subtilis twin-arginine protein transport system forms homo-multimeric complexes in its cytosolic and membrane embedded localisation.
The twin arginine translocation (Tat) system has the capacity to transfer completely folded proteins across the bacterial cytoplasmic membrane and the thylakoid membrane of plant chloroplasts. The most abundant TatA protein of this system has been suggested to form the protein conducting channel. Here, the molecular organisation of soluble and membrane embedded Bacillus subtilis TatAd was analysed using negative contrast and freeze-fractured electron microscopy. In both compartments, the protein showed homo-oligomerisation. In aqueous solution, TatAd formed homo-multimeric micelle-like complexes. Freeze-fracture analysis of proteoliposomes revealed self association of membrane-integrated TatAd independent from TatCd, the second component of this transport system. Immunogold labelling demonstrated that the substrate prePhoD was co-localised with membrane-integrated TatAd complexes.
Westermann
Martin
M
Elektronenmikroskopisches Zentrum, Klinikum der Friedrich-Schiller-Universität Jena, Ziegelmühlenweg 1, D-07743 Jena, Germany.
Pop
Ovidiu I
OI
Gerlach
Roman
R
Appel
Thomas R
TR
Schlörmann
Wiebke
W
Schreiber
Sandra
S
Müller
Jörg P
JP