For the first time ever, researchers at Uppsala University, have been able to study the process in living cells, showing that it may be more complex than previously thought.
In all living organisms, genes are regulated by proteins called transcription factors. The established model states that a gene is switched off as long as a repressing transcription factor is bound to the DNA. “The relation between transcription factor concentrations and gene expression is at the heart of biology since it describes how the concentration of proteins sets the rate of change in protein concentrations. Its position in biology is much like Newton’s law of motion in classical physics. Getting this basic relation right is very important for understanding biological systems”, says Johan Elf, professor of physical biology at Uppsala University, in a press release.
The researchers were able to test the relation directly in living cells by measuring both the binding and dissociation rates for a transcription factor to an individual binding site in the bacterial chromosome, and compare those measurements to the independently measured repression of the same gene. The researchers found small but clearly significant differences between the measurements for specific regulatory DNA sequences. This opens a large number of new possibilities for how genes are regulated in living cells.
The study is published in the online edition of Nature Genetics.