MadSci Network: Molecular Biology

Re: How does the levels of glucose affect the levels of cAMP in bacteria.

Date: Sun Jan 15 12:07:09 2006
Posted By: Mette Skinbjerg, Grad student, NINDS/NIMH, NIH
Area of science: Molecular Biology
ID: 1136824250.Mb

Dear Robert,
Hopefully this prokaryotic explanation will answer your question.
When glucose is present in the growth media, it will be transported into 
the cell by the phosphotransferase system (PTS) and phosphorylated to 
glucose-6-phosphate. The enzyme IIAglc is one of the proteins involved in 
the PTS and plays a major role in the PST cAMP regulation. IIAglc 
modulates the adenylate cyclase activity; this modulation is dependent on 
the phosphorylation state of IIAglc. In its phosphorylated form, IIAglc 
will activate adenylate cyclase, whereas, in the unphosphorylated form, 
IIAglc will inhibit adenylate cyclase activity and thereby regulate the 
cAMP levels. High glucose levels decrease the IIAglc phosphorylation, 
thus promoting the unphosphorylated form. This yields a decrease in 
adenylate cyclase activity and subsequently downregulation of cAMP 
production. On the other hand, when glucose levels are low, the 
phosphorylated form of IIAglc is enhanced, thus causing an activation of 
adenylate cyclase and an increase in cAMP levels. 

Best regards, 
Mette Skinbjerg
Peterkofsky A. 
Redistribution of phosphate pools and the regulation of Escherichia coli 
adenylate cyclase activity.
Arch Biochem Biophys. 1988 Sep;265(2):227-33. Review. 

Notley-McRobb, Death A, Ferenci T.
The relationship between external glucose concentration and cAMP levels 
inside Escherichia coli: implications for models of phosphotransferase-
mediated regulation of adenylate cyclase.
Microbiology. 1997 Jun;143 ( Pt 6):1909-18. 

ReddyP, Kamireddi M. 
Modulation of Escherichia coli adenylyl cyclase activity by catalytic-
site mutants of protein IIA(Glc) of the phosphoenolpyruvate:sugar 
phosphotransferase system.
J Bacteriol. 1998 Feb;180(3):732-6. 

Krin E, Sismeiro O, Danchin A, Bertin PN.
The regulation of Enzyme IIA(Glc) expression controls adenylate cyclase 
activity in Escherichia coli.
Microbiology. 2002 May;148(Pt 5):1553-9.

Kao KC, Tran LM, Liao JC. 
A global regulatory role of gluconeogenic genes in Escherichia coli 
revealed by transcriptome network analysis.
J Biol Chem. 2005 Oct 28;280(43):36079-87. Epub 2005 Aug 31. 

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