User:Kalearose.fajardo/Origin of transfer

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Lead[edit]

The origin of transfer (oriT) is a non-coding DNA sequence of up to 500 base pairs long on a plasmid that is necessary so that bacterial conjugation can begin.[1][2][3][4]

Bacterial conjugation occurs when a plasmid (red) in one bacterial cell is transferred to another. The transfer begins at the oriT site of the plasmid where the relaxosome protein complex binds.

Conjugation is the process by which a host bacterial cell takes up a plasmid containing target DNA, which often contains recombinant genes.[1] The first step of this process occurs when the relaxosome protein complex recognizes the oriT sequence.[5]

Article body[edit]

History[edit]

Joshua Lederberg and Edward Tatum were the first to show in 1946 that E. coli bacterium possess a method of gene transfer through a sexual process, known as bacterial conjugation.[6] The first oriT to be identified and cloned was on the RK2 (IncP) conjugative plasmid, which was done by Guiney and Helinski in 1979.[7][8]

Features[edit]

oriT sequences can be as short as 40 bp or as long as 500 bp.[4][9] The sequences vary between conjugative and nonconjugative plasmids as well as within these groups.[10] This is a cis-acting DNA region, meaning that it acts on the DNA and is transferred with it.[4] Within the oriT sequence, there is a nicn nicking region that is about 10 bp long. This is where the relaxosome first binds.[4] There is also a termination sequence upstream of the nicn site.[4]

Reaction Mechanism[edit]

A plasmid's oriT sequence serves as both a recognition point and a substrate for the enzymes in the relaxosome.[2] The first step of bacterial conjugation occurs at the nicn site of the oriT region of the plasmid. Relaxase enzymes, otherwise known as DNA strand transferases that are part of the relaxosome complex, catalyze a strand- and site-specific phosphodiester bond cleavage at the nicn site.[11]

Every plasmid's DNA only binds with a specific relaxase.[11] This reaction is a trans-esterification, which produces a nicked double-stranded DNA with the 5' end bound to a tyrosine residue in the relaxase.[11][12] The relaxase then moves toward the 3' end of the strand to unwind the DNA in the plasmid.[11]

The other strand of the plasmid, the strand that was not nicked by the relaxase, is a template for further synthesis by DNA polymerase.[11]

Once the relaxase reaches the upstream section of the oriT again where there is an inverted repeat, the process is terminated by reuniting the ends of the plasmid and releasing a single-stranded plasmid in the recipient.[4][13]

Applications[edit]

Genetic engineering[edit]

Main article: Bacterial conjugation

Conjugation allows for the transfer of target genes to many recipients, including yeast,[14] mammalian cells,[15][16] and diatoms.[17]

Diatoms could be very useful plasmid hosts as they have the potential to autotrophically produce biofuels and other chemicals.[17] There are some methods for genetic transfer for diatoms, but they are slow compared to bacterial conjugation. By designing plasmids for the diatoms P. tricornutum and T. pseudonana based on sequences for yeast and developing a method for conjugation from E. coli to the diatoms, researchers hope to advance genetic manipulation in diatoms.[17]

One of the main problems in using bacterial conjugation in genetic engineering is that certain selectable markers on the plasmids generate bacteria that have resistance to antibiotics like ampicillin and kanamycin.[18]

See also[edit]

References[edit]

  1. ^ a b Glick, Bernard R.; Patten, Cheryl L. (2017-01-01). Molecular Biotechnology: Principles and Applications of Recombinant DNA, Fifth Edition. American Society of Microbiology. doi:10.1128/9781555819378. ISBN 978-1-55581-936-1.
  2. ^ a b Zrimec, Jan; Lapanje, Aleš (2018-01-29). "DNA structure at the plasmid origin-of-transfer indicates its potential transfer range". Scientific Reports. 8 (1): 1820. doi:10.1038/s41598-018-20157-y. ISSN 2045-2322. PMC 5789077. PMID 29379098.{{cite journal}}: CS1 maint: PMC format (link)
  3. ^ De La Cruz, Fernando; Frost, Laura S.; Meyer, Richard J.; Zechner, Ellen L. (2010-01). "Conjugative DNA metabolism in Gram-negative bacteria". FEMS Microbiology Reviews. 34 (1): 18–40. doi:10.1111/j.1574-6976.2009.00195.x. ISSN 1574-6976. {{cite journal}}: Check date values in: |date= (help)
  4. ^ a b c d e f Lanka, Erich; Wilkins, Brian M. (1995-06). "DNA PROCESSING REACTIONS IN BACTERIAL CONJUGATION". Annual Review of Biochemistry. 64 (1): 141–169. doi:10.1146/annurev.bi.64.070195.001041. ISSN 0066-4154. {{cite journal}}: Check date values in: |date= (help)
  5. ^ Kiss, János; Szabó, Mónika; Hegyi, Anna; Douard, Gregory; Praud, Karine; Nagy, István; Olasz, Ferenc; Cloeckaert, Axel; Doublet, Benoît (2019). "Identification and Characterization of oriT and Two Mobilization Genes Required for Conjugative Transfer of Salmonella Genomic Island 1". Frontiers in Microbiology. 10: 457. doi:10.3389/fmicb.2019.00457. ISSN 1664-302X. PMC 6414798. PMID 30894848.{{cite journal}}: CS1 maint: PMC format (link) CS1 maint: unflagged free DOI (link)
  6. ^ Lederberg, Joshua; Tatum, E. L. (1946-10). "Gene Recombination in Escherichia Coli". Nature. 158 (4016): 558–558. doi:10.1038/158558a0. ISSN 1476-4687. {{cite journal}}: Check date values in: |date= (help)
  7. ^ Guiney, Donald G.; Helinski, Donald R. (1979-10). "The DNa-protein relaxation complex of the plasmid RK2: Location of the site-specific nick in the region of the proposed origin of transfer". Molecular and General Genetics MGG. 176 (2): 183–189. doi:10.1007/BF00273212. ISSN 0026-8925. {{cite journal}}: Check date values in: |date= (help)
  8. ^ Coupland, George M.; Brown, Anthony M. C.; Willetts, Neil S. (1987-06). "The origin of transfer (oriT) of the conjugative plasmid R46: Characterization by deletion analysis and DNA sequencing". Molecular and General Genetics MGG. 208 (1–2): 219–225. doi:10.1007/bf00330445. ISSN 0026-8925. {{cite journal}}: Check date values in: |date= (help)
  9. ^ Frost, L. S. (2009-01-01), Schaechter, Moselio (ed.), "Conjugation, Bacterial", Encyclopedia of Microbiology (Third Edition), Oxford: Academic Press, pp. 517–531, doi:10.1016/b978-012373944-5.00007-9, ISBN 978-0-12-373944-5, retrieved 2021-11-17
  10. ^ Willetts, N.; Wilkins, B. (1984-03). "Processing of plasmid DNA during bacterial conjugation". Microbiological Reviews. 48 (1): 24–41. doi:10.1128/mr.48.1.24-41.1984. ISSN 0146-0749. PMC 373001. PMID 6201705. {{cite journal}}: Check date values in: |date= (help)CS1 maint: PMC format (link)
  11. ^ a b c d e Guasch, Alicia; Lucas, María; Moncalián, Gabriel; Cabezas, Matilde; Pérez-Luque, Rosa; Gomis-Rüth, F Xavier; de la Cruz, Fernando; Coll, Miquel (2003-12-01). "Recognition and processing of the origin of transfer DNA by conjugative relaxase TrwC". Nature Structural & Molecular Biology. 10 (12): 1002–1010. doi:10.1038/nsb1017. ISSN 1545-9993.
  12. ^ Byrd, Devon R.; Matson, Steven W. (1997-09). "Nicking by transesterification: the reaction catalysed by a relaxase". Molecular Microbiology. 25 (6): 1011–1022. doi:10.1046/j.1365-2958.1997.5241885.x. ISSN 0950-382X. {{cite journal}}: Check date values in: |date= (help)
  13. ^ Lee, Catherine A.; Grossman, Alan D. (2007-10-15). "Identification of the Origin of Transfer (oriT) and DNA Relaxase Required for Conjugation of the Integrative and Conjugative Element ICEBs1 of Bacillus subtilis". Journal of Bacteriology. 189 (20): 7254–7261. doi:10.1128/JB.00932-07. PMC 2168444. PMID 17693500.{{cite journal}}: CS1 maint: PMC format (link)
  14. ^ Heinemann, Jack A.; Sprague, George F. (1989-07). "Bacterial conjugative plasmids mobilize DNA transfer between bacteria and yeast". Nature. 340 (6230): 205–209. doi:10.1038/340205a0. ISSN 0028-0836. {{cite journal}}: Check date values in: |date= (help)
  15. ^ Kunik, T.; Tzfira, T.; Kapulnik, Y.; Gafni, Y.; Dingwall, C.; Citovsky, V. (2001-02-13). "Genetic transformation of HeLa cells by Agrobacterium". Proceedings of the National Academy of Sciences. 98 (4): 1871–1876. doi:10.1073/pnas.98.4.1871. ISSN 0027-8424. PMC 29349. PMID 11172043.{{cite journal}}: CS1 maint: PMC format (link)
  16. ^ Waters, Virginia L. (2001-12). "Conjugation between bacterial and mammalian cells". Nature Genetics. 29 (4): 375–376. doi:10.1038/ng779. ISSN 1061-4036. {{cite journal}}: Check date values in: |date= (help)
  17. ^ a b c Karas, Bogumil J.; Diner, Rachel E.; Lefebvre, Stephane C.; McQuaid, Jeff; Phillips, Alex P.R.; Noddings, Chari M.; Brunson, John K.; Valas, Ruben E.; Deerinck, Thomas J.; Jablanovic, Jelena; Gillard, Jeroen T.F. (2015-11). "Designer diatom episomes delivered by bacterial conjugation". Nature Communications. 6 (1): 6925. doi:10.1038/ncomms7925. ISSN 2041-1723. PMC 4411287. PMID 25897682. {{cite journal}}: Check date values in: |date= (help)CS1 maint: PMC format (link)
  18. ^ Lopatkin, Allison J.; Meredith, Hannah R.; Srimani, Jaydeep K.; Pfeiffer, Connor; Durrett, Rick; You, Lingchong (2017-11-22). "Persistence and reversal of plasmid-mediated antibiotic resistance". Nature Communications. 8 (1): 1689. doi:10.1038/s41467-017-01532-1. ISSN 2041-1723. PMC 5698434. PMID 29162798.{{cite journal}}: CS1 maint: PMC format (link)
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