Open AccessEffect of different positively charged amino acids, C‐terminally of the signal peptidase cleavage site, on the translocation kinetics of a precursor protein in Escherichia coli K‐12
Author(s) -
Struyvé Marlies,
Bosch Dirk,
Visser Jan,
Tommassen Jan
Publication year - 1993
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.1574-6968.1993.tb06163.x
Subject(s) - amino acid , histidine , lysine , biochemistry , signal peptide , threonine , arginine , chemistry , signal peptidase , cytoplasm , cleavage (geology) , residue (chemistry) , serine , peptide sequence , biology , enzyme , paleontology , fracture (geology) , gene
of positively charged amino acids immediately downstream of the signal sequence in prokaryotic precursor proteins is known to affect the export process. However, it is not clear whether different positively charged amino acids affect the export process similarly. To investigate this, the glutamate at position +2 of outer membrane protein PhoE was substituted by arginine, lysine of histidine. Pulse‐chase experiments revealed that the Lys and Arg residues at position +2 caused a reduced processing rate, and that the effect was markedly more severe in the case of the Arg residue. Trypsin accessibility experiments revealed that the accumulated precursors were present in the cytoplasm. Since the degree of the inhibitory effect corresponded to the p K r a of the different positively charged amino acids, this suggests that the positively charged residues must be deprotonated during the secretory process.