title: The recruitment of AMP-activated protein kinase to glycogen is regulated by autophosphorylation.
abstract: The mammalian AMP-activated protein kinase (AMPK) is an obligatory αβγ heterotrimeric complex carrying a carbohydrate-binding module (CBM) in the β-subunit (AMPKβ) capable of attaching AMPK to glycogen. Nonetheless, AMPK localizes at many different cellular compartments, implying the existence of mechanisms that prevent AMPK from glycogen binding. Cell-free carbohydrate binding assays revealed that AMPK autophosphorylation abolished its carbohydrate-binding capacity. X-ray structural data of the CBM displays the central positioning of threonine 148 within the binding pocket. Substitution of Thr-148 for a phospho-mimicking aspartate (T148D) prevents AMPK from binding to carbohydrate. Overexpression of isolated CBM or β1-containing AMPK in cellular models revealed that wild type (WT) localizes to glycogen particles, whereas T148D shows a diffuse pattern. Pharmacological AMPK activation and glycogen degradation by glucose deprivation but not forskolin enhanced cellular Thr-148 phosphorylation. Cellular glycogen content was higher if pharmacological AMPK activation was combined with overexpression of T148D mutant relative to WT AMPK. In summary, these data show that glycogen-binding capacity of AMPKβ is regulated by Thr-148 autophosphorylation with likely implications in the regulation of glycogen turnover. The findings further raise the possibility of regulated carbohydrate-binding function in a wider variety of CBM-containing proteins.
authors: From the Department of Molecular Genetics, CARIM School of Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands.
authors: Yvonne
authors: Y
authors: Oligschlaeger
authors: From the Department of Molecular Genetics, CARIM School of Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands.
authors: Marie
authors: M
authors: Miglianico
authors: From the Department of Molecular Genetics, CARIM School of Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands.
authors: Dipanjan
authors: D
authors: Chanda
authors: the Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland, and.
authors: Roland
authors: R
authors: Scholz
authors: the Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland, and.
authors: Ramon F
authors: RF
authors: Thali
authors: the Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland, and.
authors: Roland
authors: R
authors: Tuerk
authors: the Florey Institute of Neuroscience and Mental Health and.
authors: David I
authors: DI
authors: Stapleton
authors: Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Victoria 3010, Australia.
authors: Paul R
authors: PR
authors: Gooley
authors: From the Department of Molecular Genetics, CARIM School of Cardiovascular Diseases, Maastricht University, 6200 MD Maastricht, The Netherlands, the Institute of Cell Biology, ETH Zurich, 8093 Zurich, Switzerland, and d.neumann@maastrichtuniversity.nl.
authors: Dietbert
authors: D
authors: Neumann
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D006003:Glycogen / Q000378:metabolism*; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D010766:Phosphorylation; D011485:Protein Binding; D011487:Protein Conformation; D021381:Protein Transport; D013912:Threonine
chemical_list: D013912:Threonine; D006003:Glycogen; D055372:AMP-Activated Protein Kinases
keywords: AMP-activated Kinase (AMPK); Autophosphorylation; Carbohydrate-binding Protein; Cellular Regulation; Glycogen; Phosphorylation; Post-translational Modification (PTM); Subcellular Localization