A naturally occurring bacterial Tat signal peptide lacking one of the 'invariant' arginine residues of the consensus targeting motif

Currently described substrates of the bacterial Tat protein transport syste m are directed for export by signal peptides containing a pair of invariant arginine residues, The signal peptide of the TtrB subunit of Salmonella en terica tetrathionate reductase contains a single arginine residue but is ne vertheless able to mediate Tat pathway transport, This naturally occurring example of a Tat signal peptide lacking a consensus arginine pair expands t he range of sequences that can target a protein to the Tat pathway. The pos sible implications of this finding for the assembly of electron transfer co mplexes containing Rieske proteins in plant organelles are discussed. (C) 2 001 Federation of European Biochemical Societies. Published by Elsevier Sci ence B.V. All rights reserved.