The basal transcription machinery for RNA polymerase II

Published on February 4, 2014   42 min

Other Talks in the Series: Epigenetics, Chromatin, Transcription and Cancer

0:00
My name's Mark Timmers. I've been interested in the process of gene regulation for a very long time, and in doing so, we've gathered a number of insights. I'm going to share with you what we've learned about the basal transcription by RNA polymerase ii.
0:15
But before we go into the details of the basal transcription process itself, it's important to review the elements which are controlling the process of transcription. These are typically, as indicated in orange here, the enhancer sequences which can be located either upstream or downstream or even in the gene, a locus control region which can act over larger distances, and the function of these DNA elements fits into the events that are happening at the start site, indicated by the arrow. And the start site is part of the core promotor sequence, which is surrounding the start site. And it's about only 50 base pairs in total sequence. Although we know that these elements are important from the simple act of looking at the DNA sequences, it's very difficult to find these functional elements.
1:03
These DNA elements function by attracting proteins. From the DNA sequence of a number of genes, we can now determine the number of genes which are involved in expression of the genome. For a simple eukaryote like yeast, which has about 6,000 genes, there's about 170 gene-specific transcription factors which bind to upstream sequences like enhancers. There's about 250 or so chromatin remodeling and modifying factors. And if we focus on the basal machinery, there's about 60 to 70 general transcription machinery proteins. In addition to this, yeast has about 20 elongation proteins and there's a number of upstream regulatory factors like kinases, ubiquitin, rare proteins, mRNA splicing proteins, export proteins. I'm not going to talk about those. So the total set is about 60 proteins which are involved in basal machinery.
1:58
If you now look at the more complex eukaryotes like ourselves, we have about 20,000 messenger RNA coding genes. There's a number of micro RNAs, and it's about 5,000 to 10,000 long non-coding RNAs. So in total, that's about 30,000 to 35,000 different RNAs which are produced by RNA polymerase. If you now look at the number of regulatory proteins, you see an expansion of the number of gene-specific transcription factors, of chromatin proteins, but the basal machinery is still comprised of about 75, in this case, general transcription machinery proteins. The elongation protein family has expanded, but what's also important is that the general machinery of yeast or human is quite similar in its makeup and the number of genes that are involved.
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The basal transcription machinery for RNA polymerase II

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