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Guanosine pentaphosphate (ppGpp), cAMP, glutathione (GSH), protein-ligand interaction, morphogene bolA


E. coli BolA is a DNA-binding transcription factor that responds to various stresses during the stationary phase by regulating the transcription of stringent response-related genes. It also protects bacteria from stressful environments by changing the cell wall morphology and inducing biofilm formation. The present study examined the physical interaction between ppGpp and cAMP to BolA by fluorescence spectroscopy. Recombinant BolA from E. coli was cloned, overexpressed, and purified to purity. BolA shows an intrinsic fluorescence light at 339 nm when excited at 280 nm, and the maximum intensity decreases in the presence of cAMP and ppGpp. The dissociation constant for ppGpp and cAMP was determined to be 164 ± 20 and 165 ± 36 µM, respectively. The experimental evaluation suggests ppGpp competes with cAMP for the ligand-binding pocket of BolA. Under stringent conditions, ppGpp bind to BolA with a strong affinity to control gene regulation and biofilm formation. However, when the cell goes back to normal environmental conditions, cAMP occupies the binding site to repress the activity of BolA. This study showed for the first time that ppGpp and cAMP bind to BolA with strong affinity.


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How to Cite

Duysak, T. (2022). BINDING OF ppGpp AND cAMP TO TRANSCRIPTIONAL REGULATOR PROTEIN BolA. Journal of Applied Biological Sciences, 16(2), 274–282. Retrieved from