A yeast FRET biosensor enlightens cAMP signaling

Area of Science:

• Cellular signaling
• Yeast physiology
• Metabolic adaptation

Background:

• The cyclic adenosine monophosphate (cAMP) and protein kinase A (PKA) signaling pathway is crucial for budding yeast's adaptation to environmental fluctuations.
• Understanding the dynamics of intracellular cAMP levels during nutrient transitions is key to deciphering yeast's adaptive strategies.

Purpose of the Study:

• To develop and utilize a Förster Resonance Energy Transfer (FRET)-based biosensor, yEPAC, for high-throughput, single-cell measurement of cAMP levels in yeast.
• To investigate the dynamics of cAMP signaling in response to sudden nutrient transitions and characterize the factors influencing these changes.

Main Methods:

• Development of yEPAC, a FRET biosensor for quantitative cAMP measurements in yeast.
• Application of yEPAC with flow cytometry for high-throughput, single-cell analysis during dynamic nutrient changes.
• Analysis of cAMP peak characteristics in response to various carbon source transitions, particularly glucose.

Main Results:

• The yEPAC sensor enabled precise, single-cell quantification of cAMP dynamics during nutrient shifts.
• A characteristic cAMP peak was observed, differentiating between carbon source transitions and showing homogeneity among cells, especially for glucose.
• The cAMP peak's magnitude correlated with the relative change in glucose concentration, adhering to the Weber-Fechner law.
• Results indicate that cAMP peak height provides information about anticipated yeast growth rates.

Conclusions:

• The yEPAC biosensor provides a powerful tool for dissecting yeast signaling and metabolic adaptation at the single-cell level.
• Yeast cAMP signaling dynamics are influenced by both extracellular cues and intracellular metabolic states.
• The observed scaling of cAMP peaks with relative environmental changes suggests an efficient information processing mechanism for predicting future growth.