Individual yeast cells signal at different levels but each with good precision

Abstract

Different isogenic cells have been shown to exhibit widely varying responses to the same extracellular signal. Based on the assumption that this variation arises from noise in the signaling pathways that cells use to transmit information from surface to nucleus, recent publications asserted that single cells cannot detect their surroundings accurately. Here, we analyze existing data on gene expression induced by the Saccharomyces cerevisiae pheromone response system, finding that individual cells signal consistently over time, implying that response variation arises primarily from stable cell-to-cell differences rather than signaling noise. Individual cells transmit at least 2.7 bits of information through the pheromone response system, enabling each cell to distinguish between at least 6 pheromone concentrations. In principle, cells can gain further precision by internally referencing these responses with measurements of constitutively expressed genes. Combination with prior results shows that only about 6% of total response variation arises from signaling pathway noise. One-sentence summarySingle yeast cells signal consistently over time, indicating that their signaling pathways transmit information precisely.