Noise Can Induce Bimodality in Positive Transcriptional Feedback Loops Without Bistability

• DOI: 10.1126/science.1178962
• Publication Date: 2010-02-25T20:17:20Z
• Authors: Tsz-Leung To; Narendra Maheshri
• Keywords: Bistability; Positive feedback; Bimodality; Negative feedback; Budding yeast; Cooperative binding; Gene regulatory network

Transcriptional positive-feedback loops are widely associated with bistability, characterized by two stable expression states that allow cells to respond analog signals in a digital manner. Using synthetic system budding yeast, we show positive feedback involving promoter multiple transcription factor (TF) binding sites can induce steady-state bimodal response without cooperative of the TF. Deterministic models this do not predict bistability. Rather, requires short-lived TF and stochastic fluctuations TF's expression. Multiple provide these fluctuations. Because many promoters possess TFs unstable, gene regulatory networks may exhibit responses, but necessarily because deterministic as is commonly thought.