Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent.
In contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli.
Department of Biological Science and Technology, National Chiao Tung University, 75 PO-Ai Street, Hsin-Chu, R.O.C., Taiwan.
Jong-Tar
JT
Kuo
Yu-Jen
YJ
Chang
Ching-Ping
CP
Tseng
D001435:Bacteriophages / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D002244:Carbon / Q000378:metabolism; D000242:Cyclic AMP / Q000378:metabolism*; D002373:Cyclic AMP Receptor Protein / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D017353:Gene Deletion; D005786:Gene Expression Regulation / Q000235:genetics; D005838:Genotype; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D007763:Lac Operon / Q000502:physiology*; D009154:Mutation; D010641:Phenotype; D010957:Plasmids / Q000235:genetics; D013045:Species Specificity; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
D002373:Cyclic AMP Receptor Protein; D006159:Guanosine Tetraphosphate; D002244:Carbon; D000242:Cyclic AMP; D001616:beta-Galactosidase