Mutations in the phosphatase domain of the 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase result in the transcriptional activation of the alternative oxidase and gluconeogenic pathways in Podospora anserina

• Published in: Fungal genetics and biology 2019-09, Vol.130, p.1-10
• Main Authors: Sellem, Carole H., Humbert, Adeline, Sainsard-Chanet, Annie
• Format: Article
• Language: English
• Subjects: Alleles; Alternative oxidase regulation; Electron Transport Complex IV - genetics; Fructose-Bisphosphatase - genetics; Fructose-Bisphosphatase - metabolism; Gene Expression Regulation, Enzymologic; Gene Expression Regulation, Fungal; Gene Knockdown Techniques; Gluconeogenesis - physiology; Glycolysis and gluconeogenesis; Mitochondria - metabolism; Mitochondrial Proteins - metabolism; Mutation; Oxidoreductases - metabolism; PFK-2/FBPase-2; Phosphoenolpyruvate Carboxykinase (ATP) - metabolism; Phosphofructokinase-2 - genetics; Phosphofructokinase-2 - metabolism; Plant Proteins - metabolism; Podospora - enzymology; Podospora - genetics; Podospora anserina; Protein Domains - genetics; Protein Isoforms; Sequence Alignment; Transcription Factors; Transcriptional Activation - genetics; Transcriptional Activation - physiology
• ISSN: 1087-1845; 1096-0937
• DOI: 10.1016/j.fgb.2019.04.005

•Inactivation of the phosphatase domain of PFK2/FBPase2 suppresses the Δcox phenotype.•The suppressor effect results from the activation of the RSEs transcription factors.•Suppression of the Δcox phenotype results from the alternative oxidase expression.•Killing the phosphatase domain of PFK-2/FBPase-2 induces the gluconeogenic enzymes.•Multiple PFK-2/FBPase-2 isoforms are present in all the species of tested Ascomycetes. By screening suppressors of a respiratory mutant lacking a functional cytochrome pathway in the filamentous fungus Podospora anserina, we isolated a mutation located in the phosphatase domain of the bi-functional enzyme 6-phosphofructo-2-kinase/fructose 2,6-bisphosphatase (PFK-2/FBPase-2). We show that the inactivation of the phosphatase but not of the kinase domain is responsible for the suppressor effect that results from the activation of the RSEs transcription factors that control expression of AOX, an alternative oxidase able to bypass the mitochondria cytochrome pathway of respiration. Remarkably, activation of the RSEs also stimulates the expression of the gluconeogenic enzymes, fructose-1,6 bi-phosphatase (FBPase-1) and phosphoenolpyruvate carboxykinase (PCK-1). We thus reveal in P. anserina an apparently paradoxical situation where the inactivation of the phosphatase domain of PFK-2/FBPase-2, supposed to stimulate glycolysis, is correlated with the transcriptional induction of the gluconeogenic enzymes. Phylogenic analysis revealed the presence of multiple presumed PFK-2/FBPase-2 isoforms in all the species of tested Ascomycetes.