# Alarmone

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{{Morefootnotes|article|date=November 2012}}
An '''alarmone''' is an [intracellular](/source/intracellular) signal molecule that is produced in [bacteria](/source/bacteria), [chloroplast](/source/chloroplast)s, and a slim minority of [archaea](/source/archaea) reacting to harsh [environmental factor](/source/environmental_factor)s.<ref name="Rinke2013">{{cite journal | vauthors = 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 | title = Insights into the phylogeny and coding potential of microbial dark matter | language = En | journal = Nature | volume = 499 | issue = 7459 | pages = 431–437 | date = July 2013 | pmid = 23851394 | doi = 10.1038/nature12352 | url = https://cloudfront.escholarship.org/dist/prd/content/qt86x4g4qw/qt86x4g4qw.pdf | doi-access = free | bibcode = 2013Natur.499..431R }}</ref> They regulate the [gene](/source/gene) expression at transcription level. Alarmones are produced in high concentrations when harsh environmental factors occur in [bacteria](/source/bacteria) and [plants](/source/plants), such as lack of [amino acid](/source/amino_acid)s, to produce [protein](/source/protein)s. Stringent factors take [uncharged tRNA](/source/uncharged_tRNA) and convert it to an alarmone. [Guanosine-5'-triphosphate](/source/Guanosine-5'-triphosphate) (GTP) is then converted to 5´-diphosphate 3´-diphosphate guanosine ([ppGpp](/source/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.<ref>{{cite journal |pmid=12023304 |year=2002 |last1=Jishage |first1=M |last2=Kvint |first2=K |last3=Shingler |first3=V |last4=Nyström |first4=T |title=Regulation of ς factor competition by the alarmone ppGpp |volume=16 |issue=10 |pages=1260–70 |doi=10.1101/gad.227902 |pmc=186289 |journal=Genes & Development |name-list-style=vanc}}</ref>

==Notes==
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==External links==
*[http://www.biology-online.org/dictionary/Alarmone Alarmone in the Biology Online Dictionary] {{Webarchive|url=https://web.archive.org/web/20091106140151/http://www.biology-online.org/dictionary/Alarmone |date=2009-11-06 }}
*[http://www.nature.com/nrmicro/journal/v3/n2/glossary/nrmicro1084_glossary.html Alarmone, Nature.com Glossary]
*{{cite journal |pmid=15109491 |year=2004 |last1=Artsimovitch |first1=I |last2=Patlan |first2=V |last3=Sekine |first3=S |last4=Vassylyeva |first4=MN |last5=Hosaka |first5=T |last6=Ochi |first6=K |last7=Yokoyama |first7=S |last8=Vassylyev |first8=DG |title=Structural basis for transcription regulation by alarmone ppGpp |volume=117 |issue=3 |pages=299–310 |journal=Cell |doi=10.1016/S0092-8674(04)00401-5 |s2cid=17943818 |name-list-style=vanc|doi-access=free }}

Category:RNA

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Adapted from the Wikipedia article [Alarmone](https://en.wikipedia.org/wiki/Alarmone) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Alarmone?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.