Editing Quorum sensing (section)

===Molecules involved===
Three-dimensional structures of proteins involved in quorum sensing were first published in 2001, when the [[crystal structure]]s of three [[LuxS]] [[Homology (biology)#Orthology|orthologs]] were determined by [[X-ray crystallography]].<ref>{{cite journal | vauthors = Lewis HA, Furlong EB, Laubert B, Eroshkina GA, Batiyenko Y, Adams JM, Bergseid MG, Marsh CD, Peat TS, Sanderson WE, Sauder JM, Buchanan SG | display-authors = 6 | title = A structural genomics approach to the study of quorum sensing: crystal structures of three LuxS orthologs | journal = Structure | volume = 9 | issue = 6 | pages = 527–537 | date = June 2001 | pmid = 11435117 | doi = 10.1016/S0969-2126(01)00613-X | doi-access = free }}</ref> In 2002, the crystal structure of the receptor LuxP of ''[[Vibrio harveyi]]'' with its inducer [[AI-2]] (which is one of the few [[biomolecules]] containing [[boron]]) bound to it was also determined.<ref>{{cite journal | vauthors = Chen X, Schauder S, Potier N, Van Dorsselaer A, Pelczer I, Bassler BL, Hughson FM | title = Structural identification of a bacterial quorum-sensing signal containing boron | journal = Nature | volume = 415 | issue = 6871 | pages = 545–549 | date = January 2002 | pmid = 11823863 | doi = 10.1038/415545a }}</ref> Many bacterial species, including ''[[E. coli]]'', an enteric bacterium and model organism for gram-negative bacteria, produce AI-2. A comparative genomic and phylogenetic analysis of 138 genomes of bacteria, [[archaea]], and eukaryotes found that "the LuxS enzyme required for AI-2 synthesis is widespread in bacteria, while the [[periplasmic space|periplasmic]] [[binding protein]] LuxP is present only in ''Vibrio'' strains," leading to the conclusion that either "other organisms may use components different from the AI-2 signal transduction system of ''Vibrio'' strains to sense the signal of AI-2 or they do not have such a quorum sensing system at all."<ref name="pmid15456522">{{cite journal | vauthors = Sun J, Daniel R, Wagner-Döbler I, Zeng AP | title = Is autoinducer-2 a universal signal for interspecies communication: a comparative genomic and phylogenetic analysis of the synthesis and signal transduction pathways | journal = BMC Evolutionary Biology | volume = 4 | issue = 1 | pages = 36 | date = September 2004 | pmid = 15456522 | pmc = 524169 | doi = 10.1186/1471-2148-4-36 | doi-access = free }}</ref> ''Vibrio'' species utilize [[Qrr RNA]]s, small non-coding RNAs, that are activated by these autoinducers to target cell density master regulators. [[Farnesol]] is used by the fungus ''[[Candida albicans]]'' as a quorum sensing molecule that inhibits [[filamentation]].<ref>{{cite journal | vauthors = Hornby JM, Jensen EC, Lisec AD, Tasto JJ, Jahnke B, Shoemaker R, Dussault P, Nickerson KW | display-authors = 6 | title = Quorum sensing in the dimorphic fungus Candida albicans is mediated by farnesol | journal = Applied and Environmental Microbiology | volume = 67 | issue = 7 | pages = 2982–2992 | date = July 2001 | pmid = 11425711 | pmc = 92970 | doi = 10.1128/AEM.67.7.2982-2992.2001 | bibcode = 2001ApEnM..67.2982H }}</ref>

A database of quorum-sensing peptides is available under the name Quorumpeps.<ref>{{cite journal | vauthors = Wynendaele E, Bronselaer A, Nielandt J, D'Hondt M, Stalmans S, Bracke N, Verbeke F, Van De Wiele C, De Tré G, De Spiegeleer B | display-authors = 6 | title = Quorumpeps database: chemical space, microbial origin and functionality of quorum sensing peptides | journal = Nucleic Acids Research | volume = 41 | issue = Database issue | pages = D655–D659 | date = January 2013 | pmid = 23180797 | pmc = 3531179 | doi = 10.1093/nar/gks1137 }}</ref><ref>{{cite journal | vauthors = Wynendaele E, Gevaert B, Stalmans S, Verbeke F, De Spiegeleer B | title = Exploring the chemical space of quorum sensing peptides | journal = Biopolymers | volume = 104 | issue = 5 | pages = 544–551 | date = September 2015 | pmid = 25846138 | doi = 10.1002/bip.22649 | s2cid = 21031922 }}</ref>

Certain bacteria can produce enzymes called [[lactonase]]s that can target and inactivate AHLs.
Researchers have developed novel molecules which block the signalling receptors of bacteria ("Quorum quenching"). mBTL is a compound that has been shown to inhibit quorum sensing and decrease the amount of cell death by a significant amount.<ref>{{cite journal | vauthors = O'Loughlin CT, Miller LC, Siryaporn A, Drescher K, Semmelhack MF, Bassler BL | title = A quorum-sensing inhibitor blocks Pseudomonas aeruginosa virulence and biofilm formation | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 110 | issue = 44 | pages = 17981–17986 | date = October 2013 | pmid = 24143808 | pmc = 3816427 | doi = 10.1073/pnas.1316981110 | bibcode = 2013PNAS..11017981O | doi-access = free }}</ref>
Additionally, researchers are also examining the role of natural compounds (such as [[caffeine]]) as potential quorum sensing inhibitors.<ref>{{cite journal | vauthors = Norizan SN, Yin WF, Chan KG | title = Caffeine as a potential quorum sensing inhibitor | journal = Sensors | volume = 13 | issue = 4 | pages = 5117–5129 | date = April 2013 | pmid = 23598500 | pmc = 3673129 | doi = 10.3390/s130405117 | bibcode = 2013Senso..13.5117N | doi-access = free }}</ref> Research in this area has been promising and could lead to the development of natural compounds as effective therapeutics.