Promoter choice: Selection vs. rejection

Abstract

The orchestration of various biological processes with high fidelity requires a precise control over temporal and spatial expression of genes. The regulation of gene expression in eukaryotes can occur at various steps, namely, transcription, m-RNA splicing, translation, and Posttranslational modifications. Transcriptional control can be achieved at any of the various stages—initiation, elongation, and termination. Initiation is marked by the assembly of the preinitiation complex at the promoter of the corresponding gene. However, at the centre of all of this is the basic process of the TF finding the right cis-regulatory motif. This is an extremely important event, as this decides when the polymerase, which is walking or hopping across the DNA molecule stops and starts synthesizing the mRNA molecules. In this article, we shall aim to propose a Rejection model, which may be followed by the basic TFs to find the right promoters for transcription. We hypothesize that the binding of TF occurs in two steps – an initial low-specificity binding event to similar cis-regulatory sequences, which may be strong or weak binding motifs, followed by a process of scrutiny and rejection of weaker binding sequences.