Characterisation of the first archaeal mannonate dehydratase from Thermoplasma acidophilum and its potential role in the catabolism of D-Mannose

Dominik Kopp, Robert Willows, Anwar Sunna*

*Corresponding author for this work

Research output: Contribution to journalArticle

1 Citation (Scopus)
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Abstract

Mannonate dehydratases catalyse the dehydration reaction from mannonate to 2-keto-3-deoxygluconate as part of the hexuronic acid metabolism in bacteria. Bacterial mannonate dehydratases present in this gene cluster usually belong to the xylose isomerase-like superfamily, which have been the focus of structural, biochemical and physiological studies. Mannonate dehydratases from archaea have not been studied in detail. Here, we identified and characterised the first archaeal mannonate dehydratase (TaManD) from the thermoacidophilic archaeon Thermoplasma acidophilum. The recombinant TaManD enzyme was optimally active at 65 degrees C and showed high specificity towards D-mannonate and its lactone, D-mannono-1,4-lactone. The gene encoding for TaManD is located adjacent to a previously studied mannose-specific aldohexose dehydrogenase (AldT) in the genome of T. acidophilum. Using nuclear magnetic resonance (NMR) spectroscopy, we showed that the mannose-specific AldT produces the substrates for TaManD, demonstrating the possibility for an oxidative metabolism of mannose in T. acidophilum. Among previously studied mannonate dehydratases, TaManD showed closest homology to enzymes belonging to the xylose isomerase-like superfamily. Genetic analysis revealed that closely related mannonate dehydratases among archaea are not located in a hexuronate gene cluster like in bacteria, but next to putative aldohexose dehydrogenases, implying a different physiological role of mannonate dehydratases in those archaeal species.

Original languageEnglish
Article number234
Pages (from-to)1-14
Number of pages14
JournalCatalysts
Volume9
Issue number3
DOIs
Publication statusPublished - Mar 2019

Bibliographical note

Copyright the Author(s) 2019. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

Keywords

  • mannonate dehydratase
  • mannose metabolism
  • Thermoplasma acidophilum
  • mannono-1,4-lactone
  • 2-keto-3-deoxygluconate
  • aldohexose dehydrogenase

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