CcpA
Encyclopedia
E-coli also has an alternative cAMP
independent catabolite repression
mechanism that utilizes a protein called catabolite repressor activator (Cra). This same mechanism is also present in Gram-positive bacteria such as Bacilus subtilis, however it is called catabolite control protein A (CcpA). In this alternative pathway CcpA negatively represses other sugar operon
s so they are off in the presence of glucose. It works by the fact that Hpr is phosphorylated
by a specific mechanism, when glucose enters through the cell membrane protein EIIC, and when Hpr is phosphoralated it can then allow CcpA to block transcription of the alternative sugar pathway operons at their respective cre sequence binding sites.
Cyclic adenosine monophosphate
Cyclic adenosine monophosphate is a second messenger important in many biological processes...
independent catabolite repression
Catabolite repression
Carbon catabolite repression, or simply catabolite repression, is an important part of global control system of various bacteria and other micro-organisms. Catabolite repression allows bacteria to adapt quickly to a preferred carbon and energy source first...
mechanism that utilizes a protein called catabolite repressor activator (Cra). This same mechanism is also present in Gram-positive bacteria such as Bacilus subtilis, however it is called catabolite control protein A (CcpA). In this alternative pathway CcpA negatively represses other sugar operon
Operon
In genetics, an operon is a functioning unit of genomic DNA containing a cluster of genes under the control of a single regulatory signal or promoter. The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo trans-splicing to create...
s so they are off in the presence of glucose. It works by the fact that Hpr is phosphorylated
Phosphorylation
Phosphorylation is the addition of a phosphate group to a protein or other organic molecule. Phosphorylation activates or deactivates many protein enzymes....
by a specific mechanism, when glucose enters through the cell membrane protein EIIC, and when Hpr is phosphoralated it can then allow CcpA to block transcription of the alternative sugar pathway operons at their respective cre sequence binding sites.