title: Mapping of O-linked beta-N-acetylglucosamine modification sites in key contractile proteins of rat skeletal muscle.
abstract: O-linked beta-N-acetylglucosamine (O-GlcNAc) is a widespread modification of serine/threonine residues of nucleocytoplasmic proteins. Recently, several key contractile proteins in rat skeletal muscle (i.e., myosin heavy and light chains and actin) were identified as O-GlcNAc modified. Moreover, it was demonstrated that O-GlcNAc moieties involved in contractile protein interactions could modulate Ca(2+) activation parameters of contraction. In order to better understand how O-GlcNAc can modulate the contractile activity of muscle fibers, we decided to identify the sites of O-GlcNAc modification in purified contractile protein homogenates. Using an MS-based method that relies on mild beta-elimination followed by Michael addition of DTT (BEMAD), we determined the localization of one O-GlcNAc site in the subdomain four of actin and four O-GlcNAc sites in the light meromyosin region of myosin heavy chains (MHC). According to previous reports concerning the role of these regions, our data suggest that O-GlcNAc sites might modulate the actin-tropomyosin interaction, and be involved in MHC polymerization or interactions between MHC and other contractile proteins. Thus, the results suggest that this PTM might be involved in protein-protein interactions but could also modulate the contractile properties of skeletal muscle.
authors.affiliation: Laboratoire de Plasticité Neuromusculaire, Unité de Neurosciences et Physiologies Adaptatives, UPRES EA 4052, IFR 147, Université des Sciences et Technologies de Lille 1, Villeneuve d'Ascq, France.
authors.forename: Julie
authors.initials: J
authors.lastname: Hédou
authors.forename: Bruno
authors.initials: B
authors.lastname: Bastide
authors.forename: Adeline
authors.initials: A
authors.lastname: Page
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Michalski
authors.forename: Willy
authors.initials: W
authors.lastname: Morelle