Signal Transduction

Transcription Takes a Back Seat

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Science  15 Mar 2013:
Vol. 339, Issue 6125, pp. 1253
DOI: 10.1126/science.339.6125.1253-a

When a bacterial cell responds to environmental changes in carbon sources available as food, how would you say this occurs—through changes in gene expression directed by appropriate transcription factors, perhaps? Berthoumieux et al. show that this seemingly likely scenario actually accounted for little of the response of Escherichia coli to nutritional stress. Rather, it was the "physiological state of the cell" that coordinated the gene expression program. That is, it was not the binding of transcription factors to particular target genes that produced the changes in gene expression in the bacteria, but instead global changes in transcription and translation mediated by changes, for example, in the abundance of RNA polymerase, ribosomes, and the pools of available amino acids and nucleotides. Mathematical modeling used to measure the relative contributions of specific transcriptional control and global changes in physiological state showed the primary mechanism to be the latter, which ironically is almost never accounted for in diagrams of cellular regulatory networks.

Mol. Syst. Biol. 9, 634 (2013).

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