guanosine tetraphosphate binding

Definition

Target type: molecularfunction

Binding to guanosine tetraphosphate (5'-ppGpp-3'), a guanosine bisphosphate having diphosphate groups at both the 3' and 5'-positions. [GOC:imk, PMID:15109491, PMID:16968770, PMID:18359660]

Guanosine tetraphosphate (ppGpp) binding is a crucial regulatory mechanism in bacteria and some eukaryotes, playing a critical role in the stringent response, a stress-induced global response that re-directs cellular resources to survival. The stringent response is triggered by nutrient starvation, particularly amino acid depletion, and it involves the synthesis of ppGpp by RelA or SpoT proteins.

ppGpp binds to various cellular targets, including RNA polymerase, ribosomes, and enzymes involved in nucleotide biosynthesis, to modulate their activity.

Specifically:

- **RNA polymerase:** ppGpp binding inhibits the transcription of rRNA and tRNA genes, reducing protein synthesis and conserving resources. This effect helps to prioritize the expression of genes involved in stress survival and amino acid biosynthesis.
- **Ribosomes:** ppGpp binding inhibits translation initiation, further reducing protein synthesis. This effect conserves resources and reduces the cellular burden of synthesizing unnecessary proteins.
- **Nucleotide biosynthesis enzymes:** ppGpp binding inhibits the activity of enzymes involved in nucleotide biosynthesis, reducing the production of nucleotides and conserving energy. This effect ensures that resources are not wasted on the production of unnecessary nucleotides.

Overall, ppGpp binding acts as a global regulatory signal, reprogramming cellular metabolism and gene expression to prioritize survival in stressful conditions. It achieves this by downregulating processes like protein synthesis and nucleotide biosynthesis while simultaneously promoting the expression of genes involved in stress adaptation.'
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Proteins (2)

Compounds (3)