Description

Guanosine-3',5'-Bisdiphosphate (also known as guanosine tetraphosphate, ppGpp or "magic spot*"), is a guanosine analogue containing a diphosphate moiety at both the 5' and 3' hydroxyls. Within the cell, ppGpp regulates transcription of genes affecting important bacterial metabolic processes, such as cell division, motility and adaptation (Potrykus, K., et al., Lemke, J.J., et al.) When prokaryotes and certain plants become nutritionally deficient, amino acid starvation is a direct consequence. During amino acid starvation, guanosine tetraphosphate is an important signal to start the stringent response mechanism. The result of the ppGpp signal is a stop in protein synthesis, leading to adjustments in gene expression levels and causing cells to remain dormant until normal nutritional levels are restored (Artsimovitch, I., et al.) In particular, ppGpp strongly inhibits the synthesis of components of the translation machinery such as tRNA and rRNA (Paul, B.J., et al., Gralla, J.D., et al.) while simultaneously stimulating the transcription of genes involved in amino acid biosynthesis (Artsimovitch, I., et al.). This ppGpp-mediated mechanism prevents the outflow of unnecessary energy resources to help bacteria survive until adequate amino acid levels are reached. Synthesis of ppGpp Guanosine tetraphosphate is synthesized from ATP and GDP during the stringent response mechanism (Figure 1). The RelA and SpoT proteins play a critical role in maintaining the appropriate levels of ppGpp (reviewed in (Potrykus, K., et al.)). Once synthesized, the ppGpp transcription factor binds to the RNA polymerase (Vrentas, C.E., et al.) to regulate the transcription of certain promoters in a process that, in E. coli, is assisted by protein DksA, Figure 2 (Paul, B.J., et al.). In the presence of ppGpp, tRNA and rRNA synthesis is reduced in favor of transcription of amino acid biosynthetic genes. Although the global role of ppGpp is understood, the mechanism by which ppGpp contributes to the regulation of certain promoters has not been fully characterized and varies among different bacteria (Bernardo, L.M., et al.) Molecular mechanisms of ppGpp are still being studied to better understand how different bacteria adapt to extreme circumstances through the stringent response. Stringent Response While ppGpp plays a critical role in cellular survival in vivo, several groups have contributed to our current knowledge of how guanosine tetraphosphate interacts with the RNA polymerase and other transcription factors by in vitro experiments (Lemke, J.J., Vrentas, C.E., Powell, B.S., deLivron, M.A. et al.). 

Product Details

Catalog NoN-6001

Purity≥85% by AX-HPLC

Extinction Coefficient13,600 Lmol-1cm-1 at 252 nm

Molecular FormulaC10H17N5O17P4 (free acid)

Molecular Weight603.20 g/mole (free acid)

Salt FormLi+

Concentration100 mM

BufferH2O

Recommended Storage-20°C or below

Other Name(s)ppGpp, Magic Spot, Guanosine tetraphosphate

Backbone3'-5'-Bisdiphosphate

Base Analog(s)Guanosine

Nucleotide CategoryBisphosphate