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<p>Living cells depend on an intricate network of chemical reactions catalysed by enzymes, which sometimes make mistakes that lead to their inactivation. Here we report a metabolite-based mechanism for preserving enzyme function in an unfavourable environment. We found that the enzyme&#xa0;TGDS produces UDP-4-keto-6-deoxyglucose, a mimic of the reaction intermediate of the enzyme UXS1, which regenerates the essential cofactor NAD<sup>+</sup> within the catalytic pocket of UXS1 by completing its catalytic cycle. Thus, the production of an ‘enzyme-rescue metabolite’ by TGDS represents a mechanism for maintaining the activity of an enzyme in a subcellular compartment where NAD<sup>+</sup> is scarce. Using a combination of in vitro and in vivo studies, we demonstrate that the inability to produce sufficient amounts of this enzyme-rescue metabolite leads to the inactivation of UXS1, impairing the synthesis of specific glycans that are crucial for skeletal development. This provides an explanation for the development of the hereditary skeletal disorder Catel–Manzke syndrome in individuals with TGDS deficiency. Defects in similar protective layers might contribute to metabolic changes in other diseases that cannot be explained with common concepts in metabolic biochemistry.</p>

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A missing enzyme-rescue metabolite as cause of a rare skeletal dysplasia

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2025年8月20日

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  • Jean Jacobs,
  • Hristiana Lyubenova,
  • Sven Potelle,
  • Johannes Kopp,
  • Isabelle Gerin,
  • Wing Lee Chan,
  • Miguel Rodriguez de los Santos,
  • Wiebke Hülsemann,
  • Martin A. Mensah,
  • Valérie Cormier-Daire,
  • Marieke Joosten,
  • Hennie T. Bruggenwirth,
  • Kyra E. Stuurman,
  • Valancy Miranda,
  • Philippe M. Campeau,
  • Lars Wittler,
  • Julie Graff,
  • Stefan Mundlos,
  • Daniel M. Ibrahim,
  • Emile Van Schaftingen,
  • Björn Fischer-Zirnsak,
  • Uwe Kornak,
  • Nadja Ehmke,
  • Guido T. Bommer

摘要

Living cells depend on an intricate network of chemical reactions catalysed by enzymes, which sometimes make mistakes that lead to their inactivation. Here we report a metabolite-based mechanism for preserving enzyme function in an unfavourable environment. We found that the enzyme TGDS produces UDP-4-keto-6-deoxyglucose, a mimic of the reaction intermediate of the enzyme UXS1, which regenerates the essential cofactor NAD+ within the catalytic pocket of UXS1 by completing its catalytic cycle. Thus, the production of an ‘enzyme-rescue metabolite’ by TGDS represents a mechanism for maintaining the activity of an enzyme in a subcellular compartment where NAD+ is scarce. Using a combination of in vitro and in vivo studies, we demonstrate that the inability to produce sufficient amounts of this enzyme-rescue metabolite leads to the inactivation of UXS1, impairing the synthesis of specific glycans that are crucial for skeletal development. This provides an explanation for the development of the hereditary skeletal disorder Catel–Manzke syndrome in individuals with TGDS deficiency. Defects in similar protective layers might contribute to metabolic changes in other diseases that cannot be explained with common concepts in metabolic biochemistry.