J. Biol. Chem., Vol. 261, Issue 24, 11021-11027, Aug, 1986
Regulation of diacylglycerol kinase biosynthesis in Escherichia coli. A trans-acting dgkR mutation increases transcription of the structural gene
JP Walsh, CR Loomis and RM Bell
The mechanism of a trans-acting mutation, dgkR1, which causes a 7-fold
elevation of diacylglycerol kinase activity in membranes (Raetz, C. R. H.,
Kantor, G. D., Nishijima, M., and Jones, M. L. (1981) J. Biol. Chem. 256,
2109-2112) was investigated by direct measurement of diacylglycerol kinase
polypeptide by high performance liquid chromatography and by construction
of fusions of the dgkA promoter to beta-galactosidase and galactokinase.
The dgkR1 mutation was demonstrated to act by increasing the transcription
of the structural gene for diacylglycerol kinase, dgkA. Additionally,
sn-glycerol-3- phosphate acyltransferase activities were shown to be
decreased 30-50% in membranes from dgkR1 mutant strains. Increased
diacylglycerol levels occurred when cells were grown on low osmolarity
media. This did not affect dgkA expression. In a dgkR+ background, enhanced
expression of sn-1,2-diacylglycerol kinase activity in cells containing a
high copy number plasmid bearing dgkA decreased sn-1,2-diacylglycerol
levels. However, overproduction of diacylglycerol kinase in a dgkR1 genetic
background did not affect diacylglycerol levels, suggesting that the dgkR1
mutation affects diacylglycerol metabolism by mechanisms additional to
enhancement of dgkA transcription.