Open AccessEvidence against the double‐arginine motif as the only determinant for protein translocation by a novel Sec‐independent pathway in Escherichia coli
Author(s) -
Brüser Thomas,
Deutzmann Rainer,
Dahl Christiane
Publication year - 1998
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1998.tb13106.x
Subject(s) - signal peptide , periplasmic space , twin arginine translocation pathway , escherichia coli , chromosomal translocation , biochemistry , peptide , arginine , biology , chemistry , peptide sequence , microbiology and biotechnology , gene , amino acid
Proteins which are synthesized with a signal peptide containing a ‘double‐arginine’ motif may be translocated across the bacterial cytoplasmic membrane by a mechanism that is different from the known Sec and signal recognition particle pathways. The function of the double‐arginine motif as a determinant for this novel pathway was studied by expressions of gene constructs coding for the high potential iron‐sulfur protein (HiPIP) from Chromatium vinosum D in Escherichia coli . When the protein was produced with its original double‐arginine motif‐containing signal peptide, it was in part translocated into the periplasm and thereby processed, as shown by immunoblots after cell fractionation and N‐terminal sequencing of purified HiPIP. Processing was not inhibited significantly by 3 mM sodium azide, indicating that translocation of HiPIP occurs by a SecA‐independent pathway. Translocation of HiPIP could be altered to the SecA‐dependent mode when its signal peptide was substituted by that of PelB from Erwinia carotovora . When the HiPIP double‐arginine motif (S RR DAVK) was introduced into the corresponding position of the PelB signal peptide, the transport pathway remained SecA‐dependent. This indicates that additional determinants are required for translocation by the Sec‐independent pathway.