title: AMPK beta subunits display isoform specific affinities for carbohydrates.
abstract: AMP-activated protein kinase (AMPK) is a heterotrimer of catalytic (alpha) and regulatory (beta and gamma) subunits with at least two isoforms for each subunit. AMPK beta1 is widely expressed whilst AMPK beta2 is highly expressed in muscle and both beta isoforms contain a mid-molecule carbohydrate-binding module (beta-CBM). Here we show that beta2-CBM has evolved to contain a Thr insertion and increased affinity for glycogen mimetics with a preference for oligosaccharides containing a single alpha-1,6 branched residue. Deletion of Thr-101 reduces affinity for single alpha-1,6 branched oligosaccharides by 3-fold, while insertion of this residue into the equivalent position in the beta1-CBM sequence increases affinity by 3-fold, confirming the functional importance of this residue.
authors.affiliation: Department of Biochemistry and Molecular Biology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Ann
authors.initials: A
authors.lastname: Koay
authors.forename: Ben
authors.initials: B
authors.lastname: Woodcroft
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Petrie
authors.forename: Helen
authors.initials: H
authors.lastname: Yue
authors.forename: Shane
authors.initials: S
authors.lastname: Emanuelle
authors.forename: Michael
authors.initials: M
authors.lastname: Bieri
authors.forename: Michael F
authors.initials: MF
authors.lastname: Bailey
authors.forename: Mark
authors.initials: M
authors.lastname: Hargreaves
authors.forename: Jong-Tae
authors.initials: JT
authors.lastname: Park
authors.forename: Kwan-Hwa
authors.initials: KH
authors.lastname: Park
authors.forename: Stuart
authors.initials: S
authors.lastname: Ralph
authors.forename: Dietbert
authors.initials: D
authors.lastname: Neumann
authors.forename: David
authors.initials: D
authors.lastname: Stapleton
authors.forename: Paul R
authors.initials: PR
authors.lastname: Gooley
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D050260:Carbohydrate Metabolism; D002240:Carbohydrate Sequence; D002417:Cattle; D019295:Computational Biology; D006003:Glycogen / Q000737:chemistry / Q000378:metabolism; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D007527:Isoenzymes; D009844:Oligosaccharides; D021122:Protein Subunits; D006003:Glycogen; D055372:AMP-Activated Protein Kinases