Open AccessThe secondary messenger ppGpp interferes with cAMP-CRP regulon by promoting CRP acetylation in Escherichia coli
Author(s) -
Chunghwan Ro,
Michael Cashel,
Llorenç Fernández-Coll
Publication year - 2021
Publication title -
plos one
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.99
H-Index - 332
ISSN - 1932-6203
DOI - 10.1371/journal.pone.0259067
Subject(s) - regulon , operon , lac operon , repressor , lac repressor , acetylation , biology , stringent response , rna polymerase , transcription (linguistics) , biochemistry , l arabinose operon , regulation of gene expression , microbiology and biotechnology , promoter , gene , gene expression , escherichia coli , linguistics , philosophy
The cAMP-CRP regulon coordinates transcription regulation of several energy-related genes, the lac operon among them. Lactose, or IPTG, induces the lac operon expression by binding to the LacI repressor, and releasing it from the promoter sequence. At the same time, the expression of the lac operon requires the presence of the CRP-cAMP complex, which promotes the binding of the RNA polymerase to the promoter region. The modified nucleotide cAMP accumulates in the absence of glucose and binds to the CRP protein, but its ability to bind to DNA can be impaired by lysine-acetylation of CRP. Here we add another layer of control, as acetylation of CRP seems to be modified by ppGpp. In cells grown in glycerol minimal media, ppGpp seems to repress the expression of lacZ , where Δ relA mutants show higher expression of lacZ than in WT. These differences between the WT and Δ relA strains seem to depend on the levels of acetylated CRP. During the growth in minimal media supplemented with glycerol, ppGpp promotes the acetylation of CRP by the Nε-lysine acetyltransferases YfiQ. Moreover, the expression of the different genes involved in the production and degradation of Acetyl-phosphate ( ackA-pta ) and the enzymatic acetylation of proteins ( yfiQ ) are stimulated by the presence of ppGpp, depending on the growth conditions.