RNA Polymerase II: Reading in Loops to get Different Tails

Ma Freire Picos

doi:10.21767/2471-8084.100016

Abstract

The DNA-loops are necessary to recycle the RNA polymerase for the multiple transcription rounds of a gene. The nascent transcript needs to be 3’-end processed: cleaved in a specific position and added a 3´-end poly-(A)-tail to become an mRNA. Under regulated conditions, genes undergo 3´-end RNA processing at different positions. This is called alternative polyadenylation (APA) and, as a consequence, mRNA molecules could have different stabilities and regulated fates. The formation of alternative DNA loops is a key factor in order to get the APA.

Highlights

The DNA-loops are necessary to recycle the RNA polymerase for the multiple transcription rounds of a gene
What happens with the RNA polymerase after a first round of transcription? It is necessary to recycle the RNA polymerase back to the promoter for a new round of transcription
It is not that simple, the major subunit of the RNA polymerase II has a Carboxy-Terminal Domain (CTD) with multiple repeats of a seven amino-acid sequence (YSTPSPS), each position can be covalently modified and there are multiple combinations possible. This was named as the CTD Code by Buratowski, a term currently in use [7,8,9,10]

Summary

Introduction

The DNA-loops are necessary to recycle the RNA polymerase for the multiple transcription rounds of a gene. The RNA polymerase II is the multi-subunit enzyme able to transcribe the protein-encoding genes in eukaryotic cells producing the messenger RNA (mRNA). Two critical steps in eukaryotic mRNA biogenesis, for its correct 3 ́-end processing are: cleavage and polyadenylation. This is necessary to achieve a message that can be recognized by the proteins that properly export it to the cytosol and so that it can be efficiently translated by the ribosomes or mediate its turnover [1,2].

Results

Conclusion