UC Berkeley

pH is tightly controlled in the cell as it influences almost all processes. Intracellular pH in Saccharomyces cerevisiae changes according to nutritional state, acidifying as the cell runs out of nutrients. We found that cytosolic acidification plays a role in transcriptional reprograming during carbon starvation. A polyglutamine domain in the SWI/SNF complex senses this pH change, enabling the induction of about 180 glucose-repressed genes. We propose that polyglutamines undergo phase transitions in a pH dependent manner, which allows glutamine transactivation domain proteins to engage and disengage in transcription. This could be a general mechanism for transcriptional reprogramming events within cells.