Protein Kinase A Regulates Gene-Specific Translational Adaptation in Differentiating Yeast

Cellular differentiation is driven by coordinately regulated changes in gene expression. Translational control of gene expression is increasingly recognized as pervasive and quantitatively significant, but the mechanisms responsible for widespread changes in gene-specific translation activity are largely unknown. Here we investigate the mechanisms responsible for translational reprogramming during cellular adaptation to the absence of glucose, a stimulus that induces invasive filamentous differentiation in yeast. We show that gene-specific translation efficiencies are highly adapted to cellular conditions and that glucose withdrawal is accompanied by widespread translational reprogramming at the level of translation initiation. We demonstrate that transcripts from <5% of genes make up the majority of translating mRNA in both rapidly dividing and starved cells. Moreover, the identities of these highly translated genes are growth-state specific, and they are subject to condition-dependent translational privilege. By comparing glucose starvation to other growth-attenuating stresses, we distinguish a glucose-specific translational response that regulates ribosomal protein and mitochondrial protein-coding genes. This response is mediated through signaling by protein kinase A (PKA). These findings reveal a high degree of growth-state specialization of the translatome and identify PKA as an important regulator of gene-specific translation activity. Overall design: Examine translational adaptation in yeast in response to glucose starvation