Structural Dynamics and Catalytic Properties of a Multimodular Xanthanase

Olga V. Moroz, Pernille F. Jensen, Sean P. McDonald, Nicholas McGregor, Elena Blagova, Gerard Comamala, Dorotea R. Segura, Lars Anderson, Santhosh M. Vasu, Vasudeva P. Rao, Lars Giger, Trine Holst Sørensen, Rune Nygaard Monrad, Allan Svendsen, Jens E. Nielsen, Bernard Henrissat, Gideon J. Davies, Harry Brumer, Kasper Dyrberg Rand, Keith S. Wilson

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Abstract

The precise catalytic strategies used for thebreakdown of the complex bacterial polysaccharide xanthan, anincreasingly frequent component of processed human food-stuffs, have remained a mystery. Here, we present character-ization of anendo-xanthanase fromPaenibacillus nanensis.Weshow that it is a CAZy family 9 glycoside hydrolase (GH9)responsible for the hydrolysis of the xanthan backbone capableof generating tetrameric xanthan oligosaccharides frompolysaccharide lyase family 8 (PL8) xanthan lyase-treatedxanthan. Three-dimensional structure determination reveals acomplex multimodular enzyme in which a catalytic (α/α)6barrel isflanked by an N-terminal“immunoglobulin-like”(Ig-like) domain (frequently found in GH9 enzymes) and by fouradditional C-terminal allβ-sheet domains that have very few homologues in sequence databases and at least one of whichfunctions as a new xanthan-binding domain, now termed CBM84. The solution-phase conformation and dynamics of the enzymein the native calcium-bound state and in the absence of calcium were probed experimentally by hydrogen/deuterium exchangemass spectrometry. Measured conformational dynamics were used to guide the protein engineering of enzyme variants withincreased stability in the absence of calcium; a property of interest for the potential use of the enzyme in cleaning detergents. Theability of hydrogen/deuterium exchange mass spectrometry to pinpoint dynamic regions of a protein under stress (e.g., removalof calcium ions) makes this technology a strong tool for improving protein catalyst properties by informed engineering.
OriginalsprogEngelsk
TidsskriftACS Catalysis
Vol/bind8
Sider (fra-til)6021-6034
ISSN2155-5435
StatusUdgivet - 2018

Emneord

  • enzyme
  • carbohydrate
  • xanthan
  • hydrogen/deuterium exchange mass spectrometry
  • enzyme stability
  • enzyme dynamics

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