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{{Short description|Sequence of bacterial DNA}}
The '''Fertility factor''' (also known as '''F factor''' or '''sex factor''') is a [[bacterial]] [[DNA]] sequence that allows a bacterium to produce a [[pilus|sex pilus]] necessary for [[bacterial conjugation|conjugation]]. It contains 20 ''tra'' (for "transfer") genes and a number of other genetic sequences responsible for incompatibility, [[DNA replication|replication]], and other functions. The F factor is an [[episome]] and can exist as an independent [[plasmid]] or integrate into the bacterial cell's [[genome]]. There are several names for the possible states:
{{too technical|date=February 2021}}
{{for multi|population factors|Fertility factor (demography) |TV series |The Sex Factor}}
The '''F-plasmid''' (first named '''F''' by one of its discoverers [[Esther Lederberg]]；also called the '''sex factor''' in ''[[E. coli]]''，the '''F sex factor''', or the '''fertility factor''')<ref name="LS">{{cite book|last1=Dugger|first1=Gordon|title=A dictionary of life sciences.|date=1976|publisher=Macmillan)|location=(London [usw.])|isbn=978-0333194362|page=130}}</ref><ref name="Hine">{{cite book|last1=Hine|first1=Robert|title=A dictionary of biology|date=2008|publisher=Oxford University Press|location=Oxford|isbn=9780199204625|page=592|edition= 6th}}</ref><ref name="FEMS">{{cite journal|last1=Lawley|first1=TD|last2=Klimke|first2=WA|last3=Gubbins|first3=MJ|last4=Frost|first4=LS|title=F factor conjugation is a true type IV secretion system.|journal=FEMS Microbiology Letters|date=15 July 2003|volume=224|issue=1|pages=1–15|pmid=12855161|doi=10.1016/S0378-1097(03)00430-0|doi-access=free}}</ref> allows genes to be transferred from one bacterium carrying the factor to another bacterium lacking the factor by [[bacterial conjugation|conjugation]]. The F factor was the first [[plasmid]] to be discovered. Unlike other plasmids, F factor is constitutive for transfer proteins due to a mutation in the gene ''finO''.<ref>{{Cite journal|last=Yoshioka|first=Y|last2=Ohtsubo|first2=H|last3=Ohtsubo|first3=E|date=1987|title=Repressor gene finO in plasmids R100 and F: constitutive transfer of plasmid F is caused by insertion of IS3 into F finO.|journal=Journal of Bacteriology|volume=169|issue=2|pages=619–623|issn=0021-9193|pmid=3027040|pmc=211823|doi=10.1128/jb.169.2.619-623.1987}}</ref> The F plasmid belongs to '''F-like plasmids''', a class of conjugative plasmids that control sexual functions of bacteria with a fertility inhibition (Fin) system.<ref name="pmid37592747">{{cite journal |last1=Frankel |first1=Gad |last2=David |first2=Sophia |last3=Low |first3=Wen Wen |last4=Seddon |first4=Chloe |last5=Wong |first5=Joshua L C |last6=Beis |first6=Konstantinos |title=Plasmids pick a bacterial partner before committing to conjugation |journal=Nucleic Acids Research |date=18 August 2023 |doi=10.1093/nar/gkad678 |pmid=37592747|doi-access=free |pmc=10516633 }}</ref>


== Discovery ==
*'''[[Hfr cell|Hfr bacteria]]''' possess F factor integrated into the bacterial [[genome]]. After integration into the host chromosomal DNA, these plasmids possess portions, or entire, F factor and portions of the bacterial [[genome]].
[[Esther Lederberg|Esther M. Lederberg]] and [[Luigi Luca Cavalli-Sforza|Luigi L. Cavalli-Sforza]] discovered "F," <ref>As written by Esther Lederberg: "At this same time, L. Cavalli in Milan Italy, discovered the phenomenon of sterility from a different angle. Exchange of data showed that if I had done an experiment, he had planned to do it, but had completed another that we had planned. So we decided to pool forces and collaborate." See http://www.estherMlederberg.com/Clark_MemorialVita/HISTORY52.html</ref> subsequently publishing with [[Joshua Lederberg]].<ref>Lederberg, J., Cavalli, L. L., and Lederberg, E. M., Nov. 1952, "Sex compatibility in Escherichia coli", Genetics 37(6):720-730</ref> Once her results were announced, two other labs joined the studies. "This was not a simultaneous independent discovery of F (I named this as Fertility Factor until it was understood.) We wrote to Hayes, Jacob, & Wollman who then proceeded with their studies."<ref>{{Cite web |title=Historical Notes About Fertility Factor F (version B) |url=http://www.esthermlederberg.com/Clark_MemorialVita/Eric%202%20FFactor5.html |access-date=2023-07-14 |website=www.esthermlederberg.com}}</ref> The discovery of "F" has sometimes been confused with [[William Hayes (geneticist)|William Hayes]]' discovery of "sex factor", though he never claimed priority. Indeed, "he [Hayes] thought F was really lambda, and when we convinced him [that it was not], he then began his work."<ref>{{Cite web |title=Historical Notes About Fertility Factor F (version A) |url=http://www.esthermlederberg.com/Clark_MemorialVita/Eric%201%20FFactor5.html |access-date=2023-07-14 |website=www.esthermlederberg.com}}</ref>


== Structure ==
⚫
*'''F<sup>+</sup> bacteria''' possess F factor as a plasmid independent of the bacterial genome. The F plasmid contains only F factor DNA and no DNA from the bacterial genome.
The most common functional segments constituting F factors are:<ref name=":0">{{Cite journal|date=2013-07-01|title=F conjugation: Back to the beginning|journal=Plasmid|language=en|volume=70|issue=1|pages=18–32|doi=10.1016/j.plasmid.2013.03.010|pmid=23632276|issn=0147-619X|last1=Arutyunov|first1=Denis|last2=Frost|first2=Laura S.}}</ref>
* OriT (Origin of Transfer): The sequence which marks the starting point of conjugative transfer.
* OriV (Origin of Vegetative Replication): The sequence starting with which the plasmid-DNA will be replicated in the recipient cell.
* tra-region ([[transfer gene]]s): Genes coding the F-Pilus and DNA transfer process.
* IS ([[Insertion sequence|Insertion Elements]]) composed of one copy of IS2, two copies of IS3, and one copy of IS1000: so-called "selfish genes" (sequence fragments which can integrate copies of themselves at different locations).<ref name="Hartwell Book">{{cite book |last1=Hartwell|first1=Leland |first2=Leroy |last2=Hood |first3=Michael L. |last3=Goldberg |first4=Ann E. |last4=Reynolds |first5=Lee M. |last5=Silver |title=Genetics:From Genes to Genomes; Fourth Edition |publisher=McGraw-Hill|year=2011 |location=New York, NY|isbn=978-0-07-352526-6 }}</ref>


Some F plasmid genes and their Function:
⚫
* '''F' (F-prime) bacteria''' possess an F plasmid that also includes some DNA taken from the bacterial genome.
* traA: F-pilin, Major subunit of the F-pilus.
* traN: recognizes cell-surface receptors<ref name="pmid37592747"/>


== Relation to the genome ==
⚫
*'''F<sup>-</sup> bacteria''' do not contain F factor.
The [[episome]] that harbors the F factor can exist as an independent [[plasmid]] or integrate into the bacterial cell's [[genome]]. There are several names for the possible states:
⚫
* '''[[Hfr cell|Hfr bacteria]]''' possess the entire F episome integrated into the bacterial genome.
⚫
* '''F<sup>+</sup> bacteria''' possess F factor as a plasmid independent of the bacterial genome. The F plasmid contains only F factor DNA and no DNA from the bacterial genome.
* '''F' (F-prime) bacteria''' are formed by incorrect excision from the chromosome, resulting in F plasmid carrying bacterial sequences that are next to where the F episome has been inserted.
⚫
* '''F<sup>−</sup> bacteria''' do not contain F factor and act as the recipients.


== Function ==
⚫
When an F<sup>+</sup> cell conjugates with an F<sup>−</sup> cell, the result is two F<sup>+</sup> cells, both capable of transmitting the plasmid further by conjugation. Unlike other plasmids, F factor is constitutive for transfer proteins due to the gene ''traJ''. This means that an F+ bacteria can always act as a donor cell. In the case of Hfr, the result are two Hfr cells. When F-prime plasmids are transferred to a recipient bacterial cell, they carry pieces of the donor's DNA that can become important in [[recombination]]. [[bioengineering|Bioengineers]] have created F plasmids that can contain inserted foreign DNA; this is called a [[fosmid]].
When an F<sup>+</sup> cell conjugates/mates with an F<sup>−</sup> cell, the result is two F<sup>+</sup> cells, both capable of transmitting the plasmid to other F<sup>−</sup> cells by conjugation. A pilus on the F+ cell interacts with the recipient cell allowing formation of a mating junction, the DNA is nicked on one strand, unwound and transferred to the recipient.<ref name="FEMS" /><ref name=":0" />


The F-plasmid belongs to a class of conjugative plasmids that control sexual functions of bacteria with a fertility inhibition (Fin) system. In this system, a trans-acting factor, FinO, and antisense RNAs, [[FinP]], combine to repress the expression of the activator gene [[TraJ 5' UTR|TraJ]]. TraJ is a [[transcription factor]] that upregulates the ''tra'' [[operon]]. The ''tra'' operon includes genes required for conjugation and plasmid transfer. This means that an F<sup>+</sup> bacteria can always act as a donor cell. The ''finO'' gene of the original F plasmid (in [[E. coli]] K12) is interrupted by an IS3 insertion, resulting in constitutive ''tra'' operon expression.<ref>{{cite journal | last = Jerome | first = LJ |author2=van Biesen T |author3=Frost LS | year = 1999 | title = Degradation of FinP antisense RNA from F-like plasmids: the RNA-binding protein, FinO, protects FinP from ribonuclease E | journal = J Mol Biol | volume = 285 | pages = 1457–1473 | pmid = 9917389 | doi = 10.1006/jmbi.1998.2404 | issue = 4}}</ref><ref name="pmid14633993">{{cite journal |vauthors=Arthur DC, Ghetu AF, Gubbins MJ, Edwards RA, Frost LS, Glover JN | title = FinO is an RNA chaperone that facilitates sense-antisense RNA interactions | journal = EMBO J. | volume = 22 | issue = 23 | pages = 6346–55 | year = 2003 | pmid = 14633993 | doi = 10.1093/emboj/cdg607 | pmc = 291848 }}</ref> F<sup>+</sup> cells also have the surface exclusion proteins TraS and TraT on the bacterial surface. These proteins prevent secondary mating events involving plasmids belonging to the same incompatibility (Inc) group. Thus, each F<sup>+</sup> bacterium can host only a single plasmid type of any given incompatibility group.
⚫
[[Category:Bacteriology]]
⚫
[[Category:Molecular genetics]]
⚫
[[Category:Microbiology]]


⚫
In the case of Hfr transfer, the resulting transconjugates are rarely Hfr. The result of Hfr/F<sup>− </sup>conjugation is a F<sup>− </sup>strain with a new genotype. When F-prime plasmids are transferred to a recipient bacterial cell, they carry pieces of the donor's DNA that can become important in [[genetic recombination|recombination]]. [[bioengineering|Bioengineers]] have created F plasmids that can contain inserted foreign DNA; this is called a [[bacterial artificial chromosome]].


The first DNA [[helicase]] ever described is encoded on the F-plasmid and is responsible for initiating plasmid transfer. It was originally called '''''[[E. coli]]'' DNA Helicase I''', but is now known as '''F-plasmid TraI'''. In addition to being a helicase, the 1756 amino acid (one of the largest in ''E. coli'') F-plasmid TraI protein is also responsible for both specific and non-specific single-stranded DNA binding as well as catalyzing the nicking of single-stranded DNA at the origin of transfer.
{{Microbiology-stub}}
{{bacteria-stub}}


==See also==
[[de:F-Plasmid]]
[[it:Plasmide F]]
* [[FlmB RNA]]
* [[Fosmid]]
[[ru:F-плазмида]]
* [[Hfr cell]]

==References==
{{Reflist|1}}

==External links==
* {{Rfam|id=RF00107|name=FinP}}
* {{Rfam|id=RF00243|name=traJ 5' UTR}}

{{Self-replicating organic structures}}

{{DEFAULTSORT:Fertility Factor}}
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[[Category:Bacteriology]]
⚫
[[Category:Molecular genetics]]
⚫
[[Category:Plasmids]]

Latest revision as of 23:22, 23 December 2024

For population factors, see Fertility factor (demography). For TV series, see The Sex Factor.

The F-plasmid (first named F by one of its discoverers Esther Lederberg；also called the sex factor in E. coli，the F sex factor, or the fertility factor)[1][2][3] allows genes to be transferred from one bacterium carrying the factor to another bacterium lacking the factor by conjugation. The F factor was the first plasmid to be discovered. Unlike other plasmids, F factor is constitutive for transfer proteins due to a mutation in the gene finO.[4] The F plasmid belongs to F-like plasmids, a class of conjugative plasmids that control sexual functions of bacteria with a fertility inhibition (Fin) system.[5]

Discovery

[edit]

Esther M. Lederberg and Luigi L. Cavalli-Sforza discovered "F," [6] subsequently publishing with Joshua Lederberg.[7] Once her results were announced, two other labs joined the studies. "This was not a simultaneous independent discovery of F (I named this as Fertility Factor until it was understood.) We wrote to Hayes, Jacob, & Wollman who then proceeded with their studies."[8] The discovery of "F" has sometimes been confused with William Hayes' discovery of "sex factor", though he never claimed priority. Indeed, "he [Hayes] thought F was really lambda, and when we convinced him [that it was not], he then began his work."[9]

Structure

[edit]

The most common functional segments constituting F factors are:[10]

  • OriT (Origin of Transfer): The sequence which marks the starting point of conjugative transfer.
  • OriV (Origin of Vegetative Replication): The sequence starting with which the plasmid-DNA will be replicated in the recipient cell.
  • tra-region (transfer genes): Genes coding the F-Pilus and DNA transfer process.
  • IS (Insertion Elements) composed of one copy of IS2, two copies of IS3, and one copy of IS1000: so-called "selfish genes" (sequence fragments which can integrate copies of themselves at different locations).[11]

Some F plasmid genes and their Function:

  • traA: F-pilin, Major subunit of the F-pilus.
  • traN: recognizes cell-surface receptors[5]

Relation to the genome

[edit]

The episome that harbors the F factor can exist as an independent plasmid or integrate into the bacterial cell's genome. There are several names for the possible states:

  • Hfr bacteria possess the entire F episome integrated into the bacterial genome.
  • F+ bacteria possess F factor as a plasmid independent of the bacterial genome. The F plasmid contains only F factor DNA and no DNA from the bacterial genome.
  • F' (F-prime) bacteria are formed by incorrect excision from the chromosome, resulting in F plasmid carrying bacterial sequences that are next to where the F episome has been inserted.
  • F− bacteria do not contain F factor and act as the recipients.

Function

[edit]

When an F+ cell conjugates/mates with an F− cell, the result is two F+ cells, both capable of transmitting the plasmid to other F− cells by conjugation. A pilus on the F+ cell interacts with the recipient cell allowing formation of a mating junction, the DNA is nicked on one strand, unwound and transferred to the recipient.[3][10]

The F-plasmid belongs to a class of conjugative plasmids that control sexual functions of bacteria with a fertility inhibition (Fin) system. In this system, a trans-acting factor, FinO, and antisense RNAs, FinP, combine to repress the expression of the activator gene TraJ. TraJ is a transcription factor that upregulates the tra operon. The tra operon includes genes required for conjugation and plasmid transfer. This means that an F+ bacteria can always act as a donor cell. The finO gene of the original F plasmid (in E. coli K12) is interrupted by an IS3 insertion, resulting in constitutive tra operon expression.[12][13] F+ cells also have the surface exclusion proteins TraS and TraT on the bacterial surface. These proteins prevent secondary mating events involving plasmids belonging to the same incompatibility (Inc) group. Thus, each F+ bacterium can host only a single plasmid type of any given incompatibility group.

In the case of Hfr transfer, the resulting transconjugates are rarely Hfr. The result of Hfr/F− conjugation is a F− strain with a new genotype. When F-prime plasmids are transferred to a recipient bacterial cell, they carry pieces of the donor's DNA that can become important in recombination. Bioengineers have created F plasmids that can contain inserted foreign DNA; this is called a bacterial artificial chromosome.

The first DNA helicase ever described is encoded on the F-plasmid and is responsible for initiating plasmid transfer. It was originally called E. coli DNA Helicase I, but is now known as F-plasmid TraI. In addition to being a helicase, the 1756 amino acid (one of the largest in E. coli) F-plasmid TraI protein is also responsible for both specific and non-specific single-stranded DNA binding as well as catalyzing the nicking of single-stranded DNA at the origin of transfer.

See also

[edit]

References

[edit]
  1. ^ Dugger, Gordon (1976). A dictionary of life sciences. (London [usw.]): Macmillan). p. 130. ISBN 978-0333194362.
  2. ^ Hine, Robert (2008). A dictionary of biology (6th ed.). Oxford: Oxford University Press. p. 592. ISBN 9780199204625.
  3. ^ a b Lawley, TD; Klimke, WA; Gubbins, MJ; Frost, LS (15 July 2003). "F factor conjugation is a true type IV secretion system". FEMS Microbiology Letters. 224 (1): 1–15. doi:10.1016/S0378-1097(03)00430-0. PMID 12855161.
  4. ^ Yoshioka, Y; Ohtsubo, H; Ohtsubo, E (1987). "Repressor gene finO in plasmids R100 and F: constitutive transfer of plasmid F is caused by insertion of IS3 into F finO". Journal of Bacteriology. 169 (2): 619–623. doi:10.1128/jb.169.2.619-623.1987. ISSN 0021-9193. PMC 211823. PMID 3027040.
  5. ^ a b Frankel, Gad; David, Sophia; Low, Wen Wen; Seddon, Chloe; Wong, Joshua L C; Beis, Konstantinos (18 August 2023). "Plasmids pick a bacterial partner before committing to conjugation". Nucleic Acids Research. doi:10.1093/nar/gkad678. PMC 10516633. PMID 37592747.
  6. ^ As written by Esther Lederberg: "At this same time, L. Cavalli in Milan Italy, discovered the phenomenon of sterility from a different angle. Exchange of data showed that if I had done an experiment, he had planned to do it, but had completed another that we had planned. So we decided to pool forces and collaborate." See http://www.estherMlederberg.com/Clark_MemorialVita/HISTORY52.html
  7. ^ Lederberg, J., Cavalli, L. L., and Lederberg, E. M., Nov. 1952, "Sex compatibility in Escherichia coli", Genetics 37(6):720-730
  8. ^ "Historical Notes About Fertility Factor F (version B)". www.esthermlederberg.com. Retrieved 2023-07-14.
  9. ^ "Historical Notes About Fertility Factor F (version A)". www.esthermlederberg.com. Retrieved 2023-07-14.
  10. ^ a b Arutyunov, Denis; Frost, Laura S. (2013-07-01). "F conjugation: Back to the beginning". Plasmid. 70 (1): 18–32. doi:10.1016/j.plasmid.2013.03.010. ISSN 0147-619X. PMID 23632276.
  11. ^ Hartwell, Leland; Hood, Leroy; Goldberg, Michael L.; Reynolds, Ann E.; Silver, Lee M. (2011). Genetics:From Genes to Genomes; Fourth Edition. New York, NY: McGraw-Hill. ISBN 978-0-07-352526-6.
  12. ^ Jerome, LJ; van Biesen T; Frost LS (1999). "Degradation of FinP antisense RNA from F-like plasmids: the RNA-binding protein, FinO, protects FinP from ribonuclease E". J Mol Biol. 285 (4): 1457–1473. doi:10.1006/jmbi.1998.2404. PMID 9917389.
  13. ^ Arthur DC, Ghetu AF, Gubbins MJ, Edwards RA, Frost LS, Glover JN (2003). "FinO is an RNA chaperone that facilitates sense-antisense RNA interactions". EMBO J. 22 (23): 6346–55. doi:10.1093/emboj/cdg607. PMC 291848. PMID 14633993.
[edit]
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