Low affinity binding between transcriptional repressor and inducer may result in poor control of gene transcription and higher gene expression noise

Transcriptional repressors play a central role in controlling gene expression at the transcription level. Specifically, repressors bind to the promoter of genes and prevent sigma factor from binding in activating gene transcription. Provision of an inducer, however, would bind the repressor, which typically result in a conformational change that led to the release of the repressor from the promoter. This would then help activate gene transcription. But, if the binding between the inducer and repressor protein is unstable or of low affinity, only a fraction of repressor would be released from the promoter through a conformational change. More importantly, this fraction of released repressors is likely to change dynamically with time, and would likely result in noisy gene expression observed for some but not all genes in RNA-seq experiments. Overall, expression noise observed for some genes in RNA-seq experiments may be due to low affinity binding between inducer and repressor of gene transcription that result in constantly changing fraction of repressor molecules able to bind to promoter of genes, and thereby, control gene transcription.