Open AccessCarbon source-dependent synthesis of SecB, a cytosolic chaperone involved in protein translocation across Escherichia coli membranes
Author(s) -
Hyuk Kyu Seoh,
Phang C. Tai
Publication year - 1997
Publication title -
journal of bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.652
H-Index - 246
eISSN - 1067-8832
pISSN - 0021-9193
DOI - 10.1128/jb.179.4.1077-1081.1997
Subject(s) - biology , cytosol , chaperone (clinical) , chromosomal translocation , escherichia coli , biochemistry , cytoplasm , membrane , glycerol , carbon source , cell membrane , microbiology and biotechnology , biophysics , gene , enzyme , medicine , pathology
SecB is a cytosolic chaperone involved in protein translocation across cytoplasmic membranes in Escherichia coli. It has been shown to be required for efficient translocation of a subset of precursor proteins but is not essential for cell viability. This study investigated whether synthesis of SecB is growth rate dependent. Interestingly, the total amount of SecB synthesized in the cells was relatively small. Moreover, the levels of SecB were found to be carbon source dependent since more SecB was produced in cells grown in glycerol media than in cells grown in glucose media, regardless of the growth rate. This is in contrast to the other Sec proteins, whose synthesis is growth rate dependent and not related to glucose as a carbon source. In addition, cyclic AMP (cAMP) partially relieves the lower levels of SecB observed in glucose medium, a compensatory effect that depends on the presence of both cya and crp gene products. Thus, the glucose-dependent synthesis of SecB may be related to the cAMP-cAMP receptor protein complex-mediated activation.