Operon

Not to be confused with Opteron or Oberon.
A typical operon

In genetics, an operon is a functioning unit of DNA containing a cluster of genes under the control of a single promoter.[1] The genes are transcribed together into an mRNA strand and either translated together in the cytoplasm, or undergo splicing to create monocistronic mRNAs that are translated separately, i.e. several strands of mRNA that each encode a single gene product. The result of this is that the genes contained in the operon are either expressed together or not at all. Several genes must be co-transcribed to define an operon.[2]

Originally, operons were thought to exist solely in prokaryotes (which includes organelles like plastids that are derived from bacteria), but their discovery in eukaryotes was shown in the early 1990s, and are considered to be rare.[3][4][5][6] In general, expression of prokaryotic operons leads to the generation of polycistronic mRNAs, while eukaryotic operons lead to monocistronic mRNAs.

Operons are also found in viruses such as bacteriophages.[7][8] For example, T7 phages have two operons. The first operon codes for various products, including a special T7 RNA polymerase which can bind to and transcribe the second operon. The second operon includes a lysis gene meant to cause the host cell to burst.[9]

  1. ^ Sadava DE, Hillis DM, Heller HC, Berenbaum M (2009). Life: The Science of Biology (9th ed.). Macmillan. p. 349. ISBN 978-1-4292-1962-4.
  2. ^ Lodish H, Zipursky L, Matsudaira P, Baltimore D, Darnel J (2000). "Chapter 9: Molecular Definition of a Gene". Molecular Cell Biology. W. H. Freeman. ISBN 978-0-7167-3136-8.
  3. ^ Kominek J, Doering DT, Opulente DA, Shen XX, Zhou X, DeVirgilio J, Hulfachor AB, Groenewald M, Mcgee MA, Karlen SD, Kurtzman CP, Rokas A, Hittinger CT (March 2019). "Eukaryotic Acquisition of a Bacterial Operon". Cell. 176 (6): 1356–1366.e10. doi:10.1016/j.cell.2019.01.034. PMC 7295392. PMID 30799038.
  4. ^ Spieth J, Brooke G, Kuersten S, Lea K, Blumenthal T (May 1993). "Operons in C. elegans: polycistronic mRNA precursors are processed by trans-splicing of SL2 to downstream coding regions". Cell. 73 (3): 521–32. doi:10.1016/0092-8674(93)90139-H. PMID 8098272. S2CID 26918553.
  5. ^ Brogna S, Ashburner M (April 1997). "The Adh-related gene of Drosophila melanogaster is expressed as a functional dicistronic messenger RNA: multigenic transcription in higher organisms". The EMBO Journal. 16 (8): 2023–31. doi:10.1093/emboj/16.8.2023. PMC 1169805. PMID 9155028.
  6. ^ Blumenthal T (November 2004). "Operons in eukaryotes". Briefings in Functional Genomics & Proteomics. 3 (3): 199–211. doi:10.1093/bfgp/3.3.199. PMID 15642184.
  7. ^ "Definition of Operon". Medical Dictionary. MedicineNet.com. Retrieved 30 December 2012.
  8. ^ Liu J, Mushegian A (July 2004). "Displacements of prohead protease genes in the late operons of double-stranded-DNA bacteriophages". Journal of Bacteriology. 186 (13): 4369–75. doi:10.1128/JB.186.13.4369-4375.2004. PMC 421614. PMID 15205439.
  9. ^ "Bacteriophage Use Operons". Prokaryotic Gene Control. Dartmouth College. Archived from the original on 28 January 2013. Retrieved 30 December 2012.