Environmentally Tuned Conservation of Adaptive Biomolecular Condensation

Cells must be able to survive a wide array of physiological stresses posed by their environment. Primordial stresses such as heat induce conserved, robust transcriptional changes across the tree of life to help cells adapt to the new environment. However, mechanisms for transcriptional activation remain incompletely characterized. Additionally, recent work has identified that reversible, specific, and adaptive stress-induced biomolecular condensates form during heat shock, but their function remains unknown. Because each response occurs near-instantaneously with the onset of increased temperature, we hypothesized that the condensation response may serve to activate the transcriptional response. In this work I characterize the growth, transcription, and condensation responses spanning three thermal niches and nearly 100 million years of evolutionary time to quantify the conserved relationship between temperature, condensation, and transcription. Through in vitro characterization of two individual condensing proteins, we show that condensation is genetically encoded and calibrated to the environment at which the source organism is adapted. We show that stress-induced biomolecular condensation is adaptive, conserved, integrated with the growth and transcriptional responses, and tuned to features of the cellular and organismal environment to initiate at niche-specific levels.