Alarmone Explained

An alarmone is an intracellular signal molecule that is produced in bacteria, chloroplasts, and a slim minority of archaea reacting to harsh environmental factors.^[1] They regulate the gene expression at transcription level. Alarmones are produced in high concentrations when harsh environmental factors occur in bacteria and plants, such as lack of amino acids, to produce proteins. Stringent factors take uncharged tRNA and convert it to an alarmone. Guanosine-5'-triphosphate (GTP) is then converted to 5´-diphosphate 3´-diphosphate guanosine (ppGpp), the archetypical alarmone. ppGpp will bind to RNA polymerase β and β´ subunits, changing promoter preference. It will decrease transcription of rRNA and other genes but will increase transcription of genes involved in amino acid biosyntheses and metabolisms involved in famine.^[2]

External links

• Alarmone in the Biology Online Dictionary
• Alarmone, Nature.com Glossary
• 15109491 . 2004 . Artsimovitch . I . Patlan . V . Sekine . S . Vassylyeva . MN . Hosaka . T . Ochi . K . Yokoyama . S . Vassylyev . DG . Structural basis for transcription regulation by alarmone ppGpp . 117 . 3 . 299–310 . Cell . 10.1016/S0092-8674(04)00401-5 . 17943818 . vanc. free .

Notes and References

1. Rinke C, Schwientek P, Sczyrba A, Ivanova NN, Anderson IJ, Cheng JF, Darling A, Malfatti S, Swan BK, Gies EA, Dodsworth JA, Hedlund BP, Tsiamis G, Sievert SM, Liu WT, Eisen JA, Hallam SJ, Kyrpides NC, Stepanauskas R, Rubin EM, Hugenholtz P, Woyke T . Insights into the phylogeny and coding potential of microbial dark matter . En . Nature . 499 . 7459 . 431–437 . July 2013 . 23851394 . 10.1038/nature12352 . free . 2013Natur.499..431R .
2. 12023304 . 2002 . Jishage . M . Kvint . K . Shingler . V . Nyström . T . Regulation of ς factor competition by the alarmone ppGpp . 16 . 10 . 1260–70 . 10.1101/gad.227902 . 186289 . Genes & Development . vanc.