Molecular pathogenesis of a new glycogenosis caused by a glycogenin-1 mutation

BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR BASIS OF DISEASE

卷:1822

Article

Nilsson, Johanna¹  Halim, Adnan²  Moslemi, Ali-Reza¹  Pedersen, Anders³  Nilsson, Jonas²  Larson, Goran²  Oldfors, Anders¹ 

[1] Univ Gothenburg, Inst Biomed, Dept Pathol, Gothenburg, Sweden

[2] Univ Gothenburg, Inst Biomed, Dept Clin Chem & Transfus Med, Gothenburg, Sweden

[3] Swedish NMR Ctr, Gothenburg, Sweden

关键词: Glycogen;    Glycogenin;    Glycogen storage disease;    Cell-free expression;    Mass spectrometry;   

DOI  :  10.1016/j.bbadis.2011.11.017

来源: Elsevier

【 摘 要 】

Glycogenin-1 initiates the glycogen synthesis in skeletal muscle by the autocatalytic formation of a short oligosaccharide at tyrosine 195. Glycogenin-1 catalyzes both the glucose-O-tyrosine linkage and the alpha 1,4 glucosidic bonds linking the glucose molecules in the oligosaccharide. We recently described a patient with glycogen depletion in skeletal muscle as a result of a non-functional glycogenin-1. The patient carried a Thr83Met substitution in glycogenin-1. In this study we have investigated the importance of threonine 83 for the catalytic activity of glycogenin-1. Non-glucosylated glycogenin-1 constructs, with various amino acid substitutions in position 83 and 195, were expressed in a cell-free expression system and autoglucosylated in vitro. The autoglucosylation was analyzed by gel-shift on western blot, incorporation of radiolabeled UDP-C-14-glucose and nano-liquid chromatography with tandem mass spectrometry (LC/MS/MS). We demonstrate that glycogenin-1 with the Thr83Met substitution is unable to form the glucose-O-tyrosine linkage at tyrosine 195 unless co-expressed with the catalytically active Tyr195Phe glycogenin-1. Our results explain the glycogen depletion in the patient expressing only Thr83Met glycogenin-1 and why heterozygous carriers without clinical symptoms show a small proportion of unglucosylated glycogenin-1. (C) 2011 Elsevier B.V. All rights reserved.

【 授权许可】

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