Alarmone
Oxford Dictionary of Biochemistry:
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alarmone
any signal molecule that serves to reorient a cell's economy in response to stress. Such molecules include ppGpp, which is produced, e.g., in microorganisms, in response to growth-rate limitation caused by amino-acid stress and acts to correct this in various ways, and diadenosine tetraphosphate (AppppA), which stimulates proliferation when DNA replication is halted at a replication fork.
| alanyl, alaninol, alanino | |
| albinism, albumin, albuminoid |
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Alarmone
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Alarmone is an intracellular signal molecule that is produced due to harsh environmental factors. 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. 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 rRNA and other genes transcription but will increase transcription of genes involved in aminoacid biosynthesis and metabolisms involved in famine [1].
External links
- Alarmone in the Biology Online Dictionary
- Alarmone, Nature.com Glossary
- Structural basis for transcription regulation by alarmone ppGpp.
Notes
- ^ Jishage M, Kvint K, Shingler V, Nyström T. Regulation of sigma factor competition by the alarmone ppGpp. Genes Dev. 2002 May 15;16(10):1260-70.
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Oxford Dictionary of Biochemistry
Oxford University Press. Oxford Dictionary of Biochemistry and Molecular Biology © 1997, 2000, 2006 All rights reserved.
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