Polygenic mRNA

In genetics, polygenic or polycistronic is the term used to describe an mRNA that is encoded by several consecutive cistrons , genetic units or genes on the DNA . Polygenic mRNAs thus contain several open reading frames (ORFs). There are short intercistronic areas between the individual cistrons , each between a stop codon as the end of the previous reading frame and a start codon as the beginning of the next reading frame.

In prokaryotes , mRNAs are predominantly polycistronic. These polycistronic mRNAs represent the transcript of several - mostly functionally related - genes on the same RNA strand. Intercistronically, there are ribosomal binding sites (RBS) with the Shine-Dalgarno sequence . A prokaryotic ribosome "recognizes" this sequence and starts with the mRNA strand to translate the nucleotide sequence in the open reading frame.

Eukaryotic mRNAs are usually monocistronic . However, there are also eukaryotes, according to Drosophila melanogaster , in which in some cases the transcript of two genes of a gene cassette is a dicistronic mRNA. Here, an internal ribosome entry point ( IRES ) located intercistronically can initiate the translation of the second cistron. One example is the stoned gene locus , which codes for two different proteins, Stoned A and Stoned B.

A polygenic mRNA is usually the transcript controlled by an operon and can only be found in prokaryotic cells or in plastids , as is the case with kinetoplastida . The difference is also that eukaryotic RNA polymerase interprets different codons for termination. However, it is possible to transcribe a complete bacterial operon in plants .

literature

NJ Trun, JE Trempy: Fundamental Bacterial Genetics. Blackwell, 2003. ISBN 0-632-04448-9 .

Individual evidence

↑ entry stoned to Inter active FLy.
↑ Leonard E. Kelly, Frances Hannan, Michelle Coulson, John Merakovsky, Michiko Smith: The stoned Locus of Drosophila melanogaster Produces a Dicistronic Transcript and Encodes Two Distinct Polypeptides . In: Genetics . tape 143 , no. 4 , August 1, 1996, ISSN 0016-6731 , p. 1699-1711 , PMID 8844157 ( genetics.org [accessed March 19, 2019]).
↑ Arimbasseri, Aneeshkumar G., Keshab Rijal, Richard J. Maraia: Transcription termination by the eukaryotic RNA polymerase III. In: Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms. Volume 1829, No. 3-4, 2012, pp. 318-330, doi: 10.1016 / j.bbagrm.2012.10.006 .
^ R. Mozes-Koch et al .: Expression of an entire bacterial operon in plants. In: Plant Physiology. Volume 158, No. 4, 2012, pp. 1883-1892, doi: 10.1104 / pp.111.186197 .

[1] try stoned to Inter active FLy.

[2] Leonard E. Kelly, Frances Hannan, Michelle Coulson, John Merakovsky, Michiko Smith: The stoned Locus of Drosophila melanogaster Produces a Dicistronic Transcript and Encodes Two Distinct Polypeptides . In: Genetics . tape 143 , no. 4 , August 1, 1996, ISSN 0016-6731 , p. 1699-1711 , PMID 8844157 ( genetics.org [accessed March 19, 2019]).

[3] Arimbasseri, Aneeshkumar G., Keshab Rijal, Richard J. Maraia: Transcription termination by the eukaryotic RNA polymerase III. In: Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms. Volume 1829, No. 3-4, 2012, pp. 318-330, doi: 10.1016 / j.bbagrm.2012.10.006 .

[4] R. Mozes-Koch et al .: Expression of an entire bacterial operon in plants. In: Plant Physiology. Volume 158, No. 4, 2012, pp. 1883-1892, doi: 10.1104 / pp.111.186197 .