Escherichia coli dnaJ deletion mutation results in loss of stability of a positive regulator, CRP.
The dnaJ deletion mutant K7052(lambda dnaK) has a temperature-sensitive defect in the synthesis of beta-galactosidase. We confirmed this operon-specific and temperature-sensitive defect in cell-free extracts prepared from the mutant cells and found that the missing factor was CRP. In the mutant, the cellular concentration of CRP was too low to allow the expression of the lac operon at a nonpermissive temperature. Introduction of a CRP over-producing plasmid into the dnaJ deletion mutant suppressed the defect of beta-galactosidase synthesis. The lower content of CRP in the mutant was found to result from extreme instability of the protein. These results strongly suggested that the heat shock protein dnaJ is involved in the stabilization (or degradation) of CRP.
Ohki
R
R
Department of Molecular Biology, School of Health Sciences, Kyorin University, Tokyo, Japan.
Kawamata
T
T
Katoh
Y
Y
Hosoda
F
F
Ohki
M
M
D001345:Autoradiography; D001426:Bacterial Proteins / Q000378:metabolism*; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D002872:Chromosome Deletion; D003001:Cloning, Molecular; D002373:Cyclic AMP Receptor Protein; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins / Q000378:metabolism*; D010957:Plasmids; D011953:Receptors, Cyclic AMP / Q000378:metabolism*; D001616:beta-Galactosidase / Q000096:biosynthesis / Q000378:metabolism
D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011953:Receptors, Cyclic AMP; D001616:beta-Galactosidase