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Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent
Author(s) -
Kuo Jong-Tar,
Chang Yu-Jen,
Tseng Ching-Ping
Publication year - 2003
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(03)01071-8
Subject(s) - lac operon , operon , stringent response , guanosine , escherichia coli , transcription (linguistics) , microbiology and biotechnology , biology , mutant , beta galactosidase , gene expression , chemistry , biochemistry , gene , linguistics , philosophy
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 .