ppGpp: stringent response and survival

J Microbiol. 2006 Feb;44(1):1-10.


Adaptation to any undesirable change in the environment dictates the survivability of many microorganisms, with such changes generating a quick and suitable response, which guides the physiology of bacteria. During nutritional deprivation, bacteria show a stringent response, as characterized by the accumulation of (p)ppGpp, resulting in the repression of stable RNA species, such as rRNA and tRNA, with a concomitant change in colony morphology. However, genes involved in amino acid biosynthesis become over-expressed to help bacteria survive under such conditions. The survivability of pathogenic bacteria inside a host cell also depends upon the stringent response demonstrated. Therefore, an understanding of the physiology of stringent conditions becomes very interesting in regulation of the growth and persistence of such invading pathogens.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Gene Expression Regulation, Bacterial
  • Gram-Negative Bacteria / growth & development*
  • Gram-Negative Bacteria / pathogenicity
  • Gram-Negative Bacteria / physiology
  • Gram-Positive Bacteria / growth & development*
  • Gram-Positive Bacteria / pathogenicity
  • Gram-Positive Bacteria / physiology
  • Guanosine Tetraphosphate / metabolism*
  • Heat-Shock Response*
  • Humans
  • Molecular Sequence Data
  • Pyrophosphatases / chemistry
  • Pyrophosphatases / genetics
  • Pyrophosphatases / metabolism


  • Bacterial Proteins
  • Guanosine Tetraphosphate
  • Pyrophosphatases