AI Article Synopsis
- * The researchers used biochemical methods and electron microscopy to analyze the structures formed when Pol II transcribes through either intact or damaged DNA within a nucleosome.
- * Their findings suggest that when Pol II backtracks during transcription, it creates an i-loop that locks the enzyme in a paused state, potentially facilitating the repair of DNA damage that is difficult to access due to the chromatin structure, especially when single-stranded binding proteins (SSBs) are present.
Article Abstract
Transcription through chromatin by RNA polymerase II (Pol II) is accompanied by the formation of small intranucleosomal DNA loops containing the enzyme (i-loops) that are involved in survival of core histones on the DNA and arrest of Pol II during the transcription of damaged DNA. However, the structures of i-loops have not been determined. Here, the structures of the intermediates formed during transcription through a nucleosome containing intact or damaged DNA were studied using biochemical approaches and electron microscopy. After RNA polymerase reaches position +24 from the nucleosomal boundary, the enzyme can backtrack to position +20, where DNA behind the enzyme recoils on the surface of the histone octamer, forming an i-loop that locks Pol II in the arrested state. Since the i-loop is formed more efficiently in the presence of SSBs positioned behind the transcribing enzyme, the loop could play a role in the transcription-coupled repair of DNA damage hidden in the chromatin structure.
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Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9454427 | PMC |
| http://dx.doi.org/10.3390/cells11172678 | DOI Listing |
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