Below is a short summary and detailed review of this video written by FutureFactual:
Eukaryotic Gene Regulation: Core Promoters, Upstream Promoters, and Enhancers
An in-depth overview of how eukaryotic gene regulation operates at the transcriptional level, contrasting with prokaryotic operons. The video explains the structure of a typical eukaryotic gene—exons, introns, transcription start site—and then focuses on promoter architecture, including the core promoter and upstream promoters. It highlights the Tata box as a common core promoter and shows how a multi-subunit transcription factor complex assembles there to recruit RNA polymerase II and initiate transcription. Upstream promoters provide additional regulatory inputs, while distal enhancers located thousands of bases away regulate transcription by looping to the promoter and boosting transcription rates.
It also introduces key players such as TBP (tata-binding protein) and transcription factors like TFIIA and TFIIB, and explains how the enhancer-promoter interaction enhances gene expression through DNA looping.
Overview of promoter architecture and transcription initiation
The video explains how a typical eukaryotic gene is organized with exons, introns, and a transcription start site, then focuses on promoter architecture. It shows that the promoter can be broken down into the core promoter and upstream promoters, with the core promoter often located about 40 bases upstream of the start site and providing the foundation for transcription initiation.
"the promoter can be broken down into the core promoter, which is basically shown in pink. This is our core promoter" - Lecturer
The core promoter and transcription factors
At the heart of transcription initiation is a large complex of transcription factors that assemble at the core promoter, guiding RNA polymerase II to the start site. The video highlights the Tata box as the most common core promoter type and introduces TBP (the Tata binding protein) and transcription factor 2B as critical players in bridging RNA polymerase II with the promoter.
"the Tata box core promoter" - Lecturer
Upstream promoters and regulatory inputs
Beyond the core promoter, upstream promoters provide additional regulatory inputs. These regions can activate or repress transcription and vary between genes, contributing to the gene-specific regulation seen across eukaryotes.
"They can either be proteins that activate transcription or proteins that repress transcription, inhibit transcription from taking place" - Lecturer
Enhancers and transcriptional activation through looping
Distal enhancers, which may lie thousands of bases away from the gene, bind specialized transcription factors. When activated, the enhancer-DNA complex loops to interact with components at the promoter, stimulating transcription and increasing the rate of gene expression.
"the enhancer can also bind special transcription factors, and when a transcription factor binds onto the enhancer, the enhancer will essentially loop around and bind onto the protein complex found on the promoter" - Lecturer