Subunit interactions in the twin-arginine translocase complex of Escherichia coli

A subset of Escherichia coli proteins, in particular cofactor-binding prote ins with so-called twin-arginine signal peptides, is transported to the per iplasm via the twin-arginine translocation (Tat) pathway. The tatA and tatB genes encode important components of the export system and we have analyse d whether the proteins encoded by these genes physically interact, Using co -immunoprecipitation experiments, we show that TatA and TatB do indeed asso ciate with each other. Gel filtration chromatograph demonstrates that both proteins are present in a large complex with an apparent molecular mass of approximately 600 kDa, indicating the presence of other components and/or s everal TatA and TatB subunits, Finally, we show that TatA is stable in the absence of TatB and may participate in a separate complex lacking TatB in w ild-type cells, (C) 2000 Federation of European Biochemical Societies.