The twin arginine (Tat) secretion pathway allows the translocation of folded proteins across
the cytoplasmic membrane of bacteria. Tat-specific signal peptides contain a characteristic
amino acid motif ((S/T) RRXFLK) including two highly conserved consecutive arginine
residues that are thought to be involved in the recognition of the signal peptides by the Tat
translocase. Here, we have analyzed the specificity of Tat signal peptide recognition by
using a genetic approach. Replacement of the two arginine residues in a Tat-specific …