Polycistron

Mitochondrial DNA is transcribed as a polycistronic RNA which is subsequently cleaved to generate the various mature mRNA, tRNA, and rRNA (Clayton, 1984). The 13 proteins encoded by mtDNA are all components of the respiratory chain and are seven subunits of complex I, one subunit of complex III, three subunits of complex IV, and two subunits of complex V. 

Liu YP, Haasnoot J, Ter Brake O, Berkhout B, Konstantinova P (2008) Inhibition of HIV-1 by multiple siRNAs expressed from a single microRNA polycistron. Nucleic Acids Res 36 2811-... 

Unlike eukaryotic cells which normally produce monoeistronic mRNA, many vimses produce polycistronic messages. DNA vimses, whieh usually replicate in... 

Careful empirical selection of the expression platform for carotenogenesis has included selection of the best strains for stability and degree of accumulation and the selection of compatible drug-resistance combinations and low copy number polycistronic plasmids to enhance product accumulation by decrease of metabolic burden." 5 Matthews and Wurtzel discussed culture and induction conditions - that have been explored in most studies. Most efforts to engineer carotenoid biosynthesis in E. coli focused on the genes and enzymes of the pathway and had a modest effect on improved accumulation. For example, substitution and over-expression of a GGPPS that uses IPP directly (discussed in... 

Figure 1-3-5. Prokaryotic Polycistronic Message Codes for Severai Different Proteins...

Hayashita Y, Osada H, Tatematsu Y et al. A polycistronic microRNA cluster, miR-17-92, is over-expressed in human lung eaneers and enhances cell proliferation. Cancer Res 2005 65 9628-9632. 

He L, Thomson JM, Hemarm MT et al. A mieroRNA polycistron as a potential human oneogene. Nature 2005 435 828-833. 

R.A. Csonka, L.N. Cloning of a polycistronic cDNA from tomato encoding... 

FIGURE 28-5 Representative prokaryotic operon. Genes A, B, and C are transcribed on one polycistronic mRNA. Typical regulatory sequences include binding sites for proteins that either activate or repress transcription from the promoter. 

In addition to the multitude of operons now known in bacteria, a few polycistronic operons have been found in the cells of lower eukaryotes. In the cells of higher eukaryotes, however, almost all protein-encoding genes are transcribed separately. 

The pathway of protein synthesis translates the three-letter alphabet of nucleotide sequences on mRNA into the twenty-letter alphabet of amino acids that constitute proteins. The mRNA is translated from its 5 -end to its 3 -end, producing a protein synthesized from its amino-terminal end to its carboxyl-terminal end. Prokaryotic mRNAs often have several coding regions, that is, they are polycistronic (see p. 420). Each coding region has its own initiation codon and produces a separate species of polypeptide. In contrast, each eukaryotic mRNA codes for only one polypeptide chain, that is, it is monocistronic. The process of translation is divided into three separate steps initiation, elongation, and termination. The polypeptide chains produced may be modified by posttranslational modification. Eukaryotic protein synthesis resembles that of prokaryotes in most details. [Note Individual differences are mentioned in the text.]... 

A single polygenic (polycistronic) mRNA is transcribed from these three genes starting at the 5 -end of the strand being synthesized... 

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