Question

Enhancers are sequences that affect the intiation kd the transcription of genes that are hundreds or thousands nucleotides away. Transcriptional activator proteins that bind to enhancers usually interact directly with transcription factors at promoters by causing the intervening DNA to loop out. An enhancer T4 does not function by looping of the DNA. Propose some other mechanism not DNA looping by which this enhancer might affect transcription at a gene thousands of nucleotides away.

Answer 1

Enhancers are the sequences that affect the initiation kd the transcription of genes that are hundreds or thousands nucleotide away. Enhancer can be located upstream of a gene, with in the coding region of gene, downstream of a gene or thousands of nucleotide away. This enhancer increase the transcription of gene.

Mechanism by which enhancer might affect transcription at a gene thousands of nucleotide away:-

Enhancer regions are binding sequences or binding sites for transcription factors.When DNA binding protein binds to enhancer, the DNA changes its shape. When the shape changes, it allow the interaction between the activators bound to the enhancers and transcription factor bound to the promoter region and the RNA polymerase to occur. Whereas DNA is generally depicted as a straight line in two dimension, and appear as three dimensional object. Therefore the Enhancer( nucleotide sequence thousands of nucleotide away) fold over and interact with a specific promoter.