ppGpp: Bacterial Signaling Molecule for Nutrient Stress and Growth Control

ppGpp (guanosine tetraphosphate) is a signaling molecule that is produced by bacteria in response to nutrient limitation or other stress conditions. When the availability of amino acids or carbon sources becomes limited, bacteria produce ppGpp to slow down growth and conserve resources. ppGpp is synthesized by the enzyme RelA and acts as a global regulator of gene expression, altering the transcription of hundreds of genes involved in metabolism, stress response, and virulence. ppGpp also plays a role in antibiotic tolerance and biofilm formation in bacteria.