Content deleted Content added
Joannamasel (talk | contribs) →Origin: add alternative ordering from recent paper |
Citation bot (talk | contribs) Alter: journal, doi, title. Add: pages, doi-access, pmc, pmid, article-number, bibcode. Removed parameters. Some additions/deletions were parameter name changes. | Use this bot. Report bugs. | Suggested by Jay8g | #UCB_toolbar |
||
Line 56:
H. Murakami and M. Sisido extended some codons to have four and five bases. [[Steven A. Benner]] constructed a functional 65th (''[[in vivo]]'') codon.<ref name="isbn0-387-22046-1">{{cite book|first=Matthew |last=Simon | name-list-style = vanc | title = Emergent Computation: Emphasizing Bioinformatics|url={{google books |plainurl=y |id=Uxg51oZNkIsC|page=105}}|date=7 January 2005|publisher=Springer Science & Business Media|isbn=978-0-387-22046-8|pages=105–106}}</ref>
In 2015 [[Nediljko Budisa|N. Budisa]], [[Dieter Söll|D. Söll]] and co-workers reported the full substitution of all 20,899 [[tryptophan]] residues (UGG codons) with unnatural thienopyrrole-alanine in the genetic code of the [[Bacteria|bacterium]] ''[[Escherichia coli|E. coli]]''.<ref>{{cite journal | last1 = Hoesl | first1 = M. G. | last2 = Oehm | first2 = S. | last3 = Durkin | first3 = P. | last4 = Darmon | first4 = E. | last5 = Peil | first5 = L. | last6 = Aerni | first6 = H.-R. | last7 = Rappsilber | first7 = J. | author-link7=Juri Rappsilber | last8 = Rinehart | first8 = J. | last9 = Leach | first9 = D. | last10 = Söll | first10 = D. | last11 = Budisa | first11 = N. | year = 2015 | title = Chemical evolution of a bacterial proteome | journal = Angewandte Chemie International Edition | volume = 54 | issue = 34 | pages = 10030–10034 | doi = 10.1002/anie.201502868 | pmc = 4782924 | pmid=26136259 | bibcode = 2015ACIE...5410030H }} NIHMSID: NIHMS711205</ref>
In 2016 the first stable semisynthetic organism was created. It was a (single cell) bacterium with two synthetic bases (called X and Y). The bases survived cell division.<ref>{{cite web|url=http://www.kurzweilai.net/first-stable-semisynthetic-organism-created|title=First stable semisynthetic organism created {{!}} KurzweilAI|date=3 February 2017|website=www.kurzweilai.net|access-date=2017-02-09}}</ref><ref>{{cite journal | vauthors = Zhang Y, Lamb BM, Feldman AW, Zhou AX, Lavergne T, Li L, Romesberg FE | title = A semisynthetic organism engineered for the stable expansion of the genetic alphabet| journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 114 | issue = 6 | pages = 1317–1322 | date = February 2017 | pmid = 28115716 | doi = 10.1073/pnas.1616443114 | pmc=5307467| bibcode = 2017PNAS..114.1317Z| doi-access = free}}</ref>
In 2017, researchers in South Korea reported that they had engineered a mouse with an extended genetic code that can produce proteins with unnatural amino acids.<ref>{{cite journal | vauthors = Han S, Yang A, Lee S, Lee HW, Park CB, Park HS | title = Expanding the genetic code of Mus musculus | journal = Nature Communications | volume = 8 |
In May 2019, researchers reported the creation of a new "Syn61" strain of the ''E. coli'' bacteria. This strain has a fully [[Synthetic biology#Synthetic life|synthetic]] genome that is refactored (all overlaps expanded), recoded (removing the use of three out of 64 codons completely), and further modified to remove the now unnecessary tRNAs and release factors. It is fully [[Genetic viability|viable]] and grows 1.6× slower than its wild-type counterpart "[[Escherichia coli#MDS42|MDS42]]".<ref name="NYT-20190515">{{cite news |last=Zimmer |first=Carl |author-link=Carl Zimmer |title=Scientists Created Bacteria With a Synthetic Genome. Is This Artificial Life? - In a milestone for synthetic biology, colonies of E. coli thrive with DNA constructed from scratch by humans, not nature. |url=https://www.nytimes.com/2019/05/15/science/synthetic-genome-bacteria.html |archive-url=https://ghostarchive.org/archive/20220102/https://www.nytimes.com/2019/05/15/science/synthetic-genome-bacteria.html |archive-date=2022-01-02 |url-access=limited |url-status=live |date=15 May 2019 |work=[[The New York Times]] |access-date=16 May 2019 }}{{cbignore}}</ref><ref name="NAT-20190515">{{cite journal |author=Fredens, Julius |s2cid=205571025 |display-authors=et al. |title=Total synthesis of Escherichia coli with a recoded genome |date=15 May 2019 |journal=[[Nature (journal)|Nature]] |volume=569 |issue=7757 |pages=514–518 |doi=10.1038/s41586-019-1192-5 |pmid=31092918 |pmc=7039709 |bibcode=2019Natur.569..514F }}</ref>
Line 183:
==Origin==
The genetic code is a key part of the [[origin of life|history of life]]. Under the [[RNA world hypothesis]], self-replicating RNA molecules preceded significant use of proteins. Under the nucleopeptide world hypothesis, significant use of peptides preceded the genetic code and was concurrent with life's sophisticated use of RNA.<ref>{{cite journal |last1=Fried |first1=Stephen D. |last2=Fujishima |first2=Kosuke |last3=Makarov |first3=Mikhail |last4=Cherepashuk |first4=Ivan |last5=Hlouchova |first5=Klara |title=Peptides before and during the nucleotide world: an origins story emphasizing cooperation between proteins and nucleic acids |journal=Journal of
A hypothetical randomly evolved genetic code further motivates a biochemical or evolutionary model for its origin. If amino acids were randomly assigned to triplet codons, there would be 1.5 × 10<sup>84</sup> possible genetic codes.<ref name="isbn0-674-05075-4">{{cite book|first=Michael |last=Yarus|author-link=Michael Yarus|title=Life from an RNA World: The Ancestor Within|url={{google books |plainurl=y |id=-YLBMmJE1WwC}}|year=2010|publisher=Harvard University Press|isbn=978-0-674-05075-4}}</ref>{{rp|[{{google books |plainurl=y |id=-YLBMmJE1WwC|page=163}} 163]}} This number is found by calculating the number of ways that 21 items (20 amino acids plus one stop) can be placed in 64 bins, wherein each item is used at least once.<ref>{{Cite web|url=http://community.wolfram.com/groups/-/m/t/319970|title=Mathematica function for # possible arrangements of items in bins? – Online Technical Discussion Groups—Wolfram Community|website=community.wolfram.com|language=en-US|access-date=2017-02-03}}</ref> However, the distribution of codon assignments in the genetic code is nonrandom.<ref name="pmid9732450">{{cite journal | vauthors = Freeland SJ, Hurst LD | s2cid = 20130470 | title = The genetic code is one in a million | journal = Journal of Molecular Evolution | volume = 47 | issue = 3 | pages = 238–48 | date = Sep 1998 | pmid = 9732450 | doi = 10.1007/PL00006381 | bibcode = 1998JMolE..47..238F }}</ref> In particular, the genetic code clusters certain amino acid assignments.
Line 199:
Hypotheses have addressed a variety of scenarios:<ref name="pmid10366854">{{cite journal | vauthors = Knight RD, Freeland SJ, Landweber LF | title = Selection, history and chemistry: the three faces of the genetic code | journal = Trends in Biochemical Sciences | volume = 24 | issue = 6 | pages = 241–7 | date = Jun 1999 | pmid = 10366854|doi=10.1016/S0968-0004(99)01392-4|url=https://www.sciencedirect.com/science/article/abs/pii/S0968000499013924| url-access = subscription }}</ref>
* Chemical principles govern specific RNA interaction with amino acids. Experiments with [[aptamer]]s showed that some amino acids have a selective chemical affinity for their codons.<ref name="pmid9751648">{{cite journal | vauthors = Knight RD, Landweber LF | title = Rhyme or reason: RNA-arginine interactions and the genetic code | journal = Chemistry & Biology | volume = 5 | issue = 9 | pages = R215–20 | date = Sep 1998 | pmid = 9751648 | doi = 10.1016/S1074-5521(98)90001-1 | doi-access = free }}</ref> Experiments showed that of 8 amino acids tested, 6 show some RNA triplet-amino acid association.<ref name="isbn0-674-05075-4" /><ref name="pmid19795157">{{cite journal | vauthors = Yarus M, Widmann JJ, Knight R | title = RNA-amino acid binding: a stereochemical era for the genetic code | journal = Journal of Molecular Evolution | volume = 69 | issue = 5 | pages = 406–29 | date = Nov 2009 | pmid = 19795157 | doi = 10.1007/s00239-009-9270-1 | bibcode = 2009JMolE..69..406Y | doi-access = free }}</ref>
* Biosynthetic expansion. The genetic code grew from a simpler earlier code through a process of "biosynthetic expansion". Primordial life "discovered" new amino acids (for example, as by-products of [[metabolism]]) and later incorporated some of these into the machinery of genetic coding.<ref>{{cite journal | vauthors = Sengupta S, Higgs PG | s2cid = 15542587 | year = 2015 | title = Pathways of genetic code evolution in ancient and modern organisms | journal = Journal of Molecular Evolution | volume = 80 | issue = 5–6| pages = 229–243 | doi=10.1007/s00239-015-9686-8 | pmid=26054480| bibcode = 2015JMolE..80..229S}}</ref> Although much circumstantial evidence has been found to suggest that fewer amino acid types were used in the past,<ref name="pmid12270892">{{cite journal | vauthors = Brooks DJ, Fresco JR, Lesk AM, Singh M | title = Evolution of amino acid frequencies in proteins over deep time: inferred order of introduction of amino acids into the genetic code | journal = Molecular Biology and Evolution | volume = 19 | issue = 10 | pages = 1645–55 | date = Oct 2002 | pmid = 12270892 | doi = 10.1093/oxfordjournals.molbev.a003988 | doi-access = free }}</ref> precise and detailed hypotheses about which amino acids entered the code in what order are controversial.<ref name="pmid9115171">{{cite journal | vauthors = Amirnovin R | s2cid = 23334860 | title = An analysis of the metabolic theory of the origin of the genetic code | journal = Journal of Molecular Evolution | volume = 44 | issue = 5 | pages = 473–6 | date = May 1997 | pmid = 9115171 | doi = 10.1007/PL00006170 | bibcode = 1997JMolE..44..473A }}</ref><ref name="pmid11087835">{{cite journal | vauthors = Ronneberg TA, Landweber LF, Freeland SJ | title = Testing a biosynthetic theory of the genetic code: fact or artifact? | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 97 | issue = 25 | pages = 13690–5 | date = Dec 2000 | pmid = 11087835 | pmc = 17637 | doi = 10.1073/pnas.250403097 | bibcode = 2000PNAS...9713690R | doi-access = free }}</ref> However, several studies have suggested that Gly, Ala, Asp, Val, Ser, Pro, Glu, Leu, Thr may belong to a group of early-addition amino acids, whereas Cys, Met, Tyr, Trp, His, Phe may belong to a group of later-addition amino acids.<ref>{{Cite journal|last=Trifonov|first=Edward N.|date=September 2009|title=The origin of the genetic code and of the earliest oligopeptides|url=https://linkinghub.elsevier.com/retrieve/pii/S0923250809000576|journal=Research in Microbiology|language=en|volume=160|issue=7|pages=481–486|doi=10.1016/j.resmic.2009.05.004|pmid=19524038|url-access=subscription}}</ref><ref>{{Cite journal|last1=Higgs|first1=Paul G.|last2=Pudritz|first2=Ralph E.|date=June 2009|title=A Thermodynamic Basis for Prebiotic Amino Acid Synthesis and the Nature of the First Genetic Code|url=http://www.liebertpub.com/doi/10.1089/ast.2008.0280|journal=Astrobiology|language=en|volume=9|issue=5|pages=483–490|doi=10.1089/ast.2008.0280|pmid=19566427|issn=1531-1074|arxiv=0904.0402|bibcode=2009AsBio...9..483H|s2cid=9039622}}</ref><ref>{{Cite journal|last1=Chaliotis|first1=Anargyros|last2=Vlastaridis|first2=Panayotis|last3=Mossialos|first3=Dimitris|last4=Ibba|first4=Michael|last5=Becker|first5=Hubert D.|last6=Stathopoulos|first6=Constantinos|last7=Amoutzias|first7=Grigorios D.|date=2017-02-17|title=The complex evolutionary history of aminoacyl-tRNA synthetases|url= |journal=Nucleic Acids Research|language=en|volume=45|issue=3|pages=1059–1068|doi=10.1093/nar/gkw1182|issn=0305-1048|pmc=5388404|pmid=28180287}}</ref><ref>{{Cite journal|last1=Ntountoumi|first1=Chrysa|last2=Vlastaridis|first2=Panayotis|last3=Mossialos|first3=Dimitris|last4=Stathopoulos|first4=Constantinos|last5=Iliopoulos|first5=Ioannis|last6=Promponas|first6=Vasilios|last7=Oliver|first7=Stephen G|last8=Amoutzias|first8=Grigoris D|date=2019-11-04|title=Low complexity regions in the proteins of prokaryotes perform important functional roles and are highly conserved|url= |journal=Nucleic Acids Research|language=en|volume=47|issue=19|pages=9998–10009|doi=10.1093/nar/gkz730|issn=0305-1048|pmc=6821194|pmid=31504783}}</ref> An alternative analysis of amino acid usage in the [[Last Universal Common Ancestor]] concluded that the amino acids came in the following order: Val, Gly, Ile, Met, Ala, Thr, His, Glu, Cys, Pro, Lys, Ser, Asp, Leu, Asn, Arg, Phe, Tyr, Gln, Trp.<ref name="wehbi2024">{{cite journal |last1=Wehbi |first1=Sawsan |last2=Wheeler |first2=Andrew |last3=Morel |first3=Benoit |last4=Manepalli |first4=Nandini |last5=Minh |first5=Bui Quang |last6=Lauretta |first6=Dante S. |last7=Masel |first7=Joanna |title=Order of amino acid recruitment into the genetic code resolved by last universal common
* Natural selection has led to codon assignments of the genetic code that minimize the effects of [[mutation]]s.<ref name="pmid14604186">{{cite journal | vauthors = Freeland SJ, Wu T, Keulmann N | s2cid = 18823745 | title = The case for an error minimizing standard genetic code | journal = Origins of Life and Evolution of the Biosphere | volume = 33 | issue = 4–5 | pages = 457–77 | date = Oct 2003 | pmid = 14604186 | doi = 10.1023/A:1025771327614 | bibcode = 2003OLEB...33..457F }}</ref> A recent hypothesis<ref name="pmid19479032">{{cite journal | vauthors = Baranov PV, Venin M, Provan G | title = Codon size reduction as the origin of the triplet genetic code | journal = PLOS ONE | volume = 4 | issue = 5 | pages = e5708 | date = 2009 | pmid = 19479032 | pmc = 2682656 | doi = 10.1371/journal.pone.0005708 | editor1-last = Gemmell | bibcode = 2009PLoSO...4.5708B | editor1-first = Neil John | doi-access = free }}</ref> suggests that the triplet code was derived from codes that used longer than triplet codons (such as quadruplet codons). Longer than triplet decoding would increase codon redundancy and would be more error resistant. This feature could allow accurate decoding absent complex translational machinery such as the [[ribosome]], such as before cells began making ribosomes.
* Information channels: [[information theory|Information-theoretic]] approaches model the process of translating the genetic code into corresponding amino acids as an error-prone information channel.<ref name="pmid17826800">{{cite journal | vauthors = Tlusty T | title = A model for the emergence of the genetic code as a transition in a noisy information channel | journal = Journal of Theoretical Biology | volume = 249 | issue = 2 | pages = 331–42 | date = Nov 2007 | pmid = 17826800 | doi = 10.1016/j.jtbi.2007.07.029 | arxiv = 1007.4122 | bibcode = 2007JThBi.249..331T | s2cid = 12206140 }}</ref> The inherent noise (that is, the error) in the channel poses the organism with a fundamental question: how can a genetic code be constructed to withstand noise<ref>{{cite book | vauthors = Sonneborn TM | veditors =Bryson V, Vogel H | title = Evolving genes and proteins |publisher=Academic Press|___location=New York |date=1965|pages=377–397}}</ref> while accurately and efficiently translating information? These [[rate-distortion theory|"rate-distortion"]] models<ref name="pmid 18352335">{{cite journal | vauthors = Tlusty T | title = Rate-distortion scenario for the emergence and evolution of noisy molecular codes | journal = Physical Review Letters | volume = 100 | issue = 4 |
*Game theory: Models based on [[signaling game]]s combine elements of game theory, natural selection and information channels. Such models have been used to suggest that the first polypeptides were likely short and had non-enzymatic function. Game theoretic models suggested that the organization of RNA strings into cells may have been necessary to prevent "deceptive" use of the genetic code, i.e. preventing the ancient equivalent of viruses from overwhelming the RNA world.<ref name="pmid23985735">{{cite journal | vauthors = Jee J, Sundstrom A, Massey SE, Mishra B | title = What can information-asymmetric games tell us about the context of Crick's 'frozen accident'? | journal = Journal of the Royal Society, Interface | volume = 10 | issue = 88 | pages = 20130614 | date = Nov 2013 | pmid = 23985735 | pmc = 3785830 | doi = 10.1098/rsif.2013.0614 }}</ref>
*Stop codons: Codons for translational stops are also an interesting aspect to the problem of the origin of the genetic code. As an example for addressing stop codon evolution, it has been suggested that the stop codons are such that they are most likely to terminate translation early in the case of a [[frame shift]] error.<ref>{{cite journal | vauthors = Itzkovitz S, Alon U | title = The genetic code is nearly optimal for allowing additional information within protein-coding sequences | journal = Genome Research | volume = 17| issue = 4 | pages = 405–412 | date = 2007| doi = 10.1101/gr.5987307 | pmid=17293451 | pmc=1832087}}</ref> In contrast, some stereochemical molecular models explain the origin of stop codons as "unassignable".<ref name="pmid21779963"/>
| |||