Positive feedback induces switch between distributive and processive phosphorylation of Hog1

• Published in: Nature communications 2023-04, Vol.14 (1), p.2477-2477, Article 2477
• Main Authors: Mosbacher, Maximilian, Lee, Sung Sik, Yaakov, Gilad, Nadal-Ribelles, Mariona, de Nadal, Eulàlia, van Drogen, Frank, Posas, Francesc, Peter, Matthias, Claassen, Manfred
• Format: Article
• Language: English
• Subjects: 13; 13/62; 14/35; 14/63; 631/553/2695; 631/553/2700; 631/553/2712; 631/553/2715; Affinity; Decision making; Feedback; Feedback loops; Hog1 protein; Humanities and Social Sciences; Kinases; MAP kinase; Mathematical models; Mitogen-Activated Protein Kinase Kinases - metabolism; Mitogen-Activated Protein Kinases - genetics; Mitogen-Activated Protein Kinases - metabolism; multidisciplinary; Perturbation; Phosphorylation; Positive feedback; Robustness (mathematics); Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Science; Science (multidisciplinary); Signal transduction; Switches; Yeasts
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-37430-y

Cellular decision making often builds on ultrasensitive MAPK pathways. The phosphorylation mechanism of MAP kinase has so far been described as either distributive or processive, with distributive mechanisms generating ultrasensitivity in theoretical analyses. However, the in vivo mechanism of MAP kinase phosphorylation and its activation dynamics remain unclear. Here, we characterize the regulation of the MAP kinase Hog1 in Saccharomyces cerevisiae via topologically different ODE models, parameterized on multimodal activation data. Interestingly, our best fitting model switches between distributive and processive phosphorylation behavior regulated via a positive feedback loop composed of an affinity and a catalytic component targeting the MAP kinase-kinase Pbs2. Indeed, we show that Hog1 directly phosphorylates Pbs2 on serine 248 (S248), that cells expressing a non-phosphorylatable (S248A) or phosphomimetic (S248E) mutant show behavior that is consistent with simulations of disrupted or constitutively active affinity feedback and that Pbs2-S248E shows significantly increased affinity to Hog1 in vitro. Simulations further suggest that this mixed Hog1 activation mechanism is required for full sensitivity to stimuli and to ensure robustness to different perturbations. How cells shape signalling dynamics in MAPK cascades remains unclear. Here the authors combine mathematical modelling with in vivo validation to uncover a novel feedback mechanism that increases processivity and robustness of the yeast Hog1 module.