Organization of a functional glycolytic metabolon on mitochondria for metabolic efficiency
Haoming Wang, John Vant, Andrew Zhang, Richard G. Sánchez, Youjun Wu, Mary Lauren Micou, Vincent Luczak, Zachary Whiddon, Natasha M. Carlson, Seungyoon B. Yu, Mirna Jabbo, Seok‐Jun Yoon, Ahmed A. Abushawish, Majid Ghassemian, Takeya Masubuchi, Quan Gan, Shigeki Watanabe, Eric R. Griffis, Marc Hammarlund, Abhishek Singharoy, Gülçin Pekkurnaz
Abstract
Glucose, the primary cellular energy source, is metabolized through glycolysis initiated by the rate-limiting enzyme hexokinase (HK). In energy-demanding tissues like the brain, HK1 is the dominant isoform, primarily localized on mitochondria, and is crucial for efficient glycolysis-oxidative phosphorylation coupling and optimal energy generation. This study unveils a unique mechanism regulating HK1 activity, glycolysis and the dynamics of mitochondrial coupling, mediated by the metabolic sensor enzyme O-GlcNAc transferase (OGT). OGT catalyses reversible O-GlcNAcylation, a post-translational modification influenced by glucose flux. Elevated OGT activity induces dynamic O-GlcNAcylation of the regulatory domain of HK1, subsequently promoting the assembly of the glycolytic metabolon on the outer mitochondrial membrane. This modification enhances the mitochondrial association with HK1, orchestrating glycolytic and mitochondrial ATP production. Mutation in HK1's O-GlcNAcylation site reduces ATP generation in multiple cell types, specifically affecting metabolic efficiency in neurons. This study reveals a previously unappreciated pathway that links neuronal metabolism and mitochondrial function through OGT and the formation of the glycolytic metabolon, providing potential strategies for tackling metabolic and neurological disorders.