NMR assignment and functional characterization of biotechnologically modified xanthan
- 1Norwegian University of Science and Technology
Abstract
Xanthan gum is one of the most important industrial microbial polysaccharides, yet comprehensive molecular-level structural characterization remains limited because of its high molecular weight, conformational rigidity, and severe spectral overlap in nuclear magnetic resonance spectroscopy. Here, we present a near-complete 1H/13C NMR chemical shift assignment of the xanthan repeating unit by combining multidimensional NMR spectroscopy with targeted glycosyltransferase knockout strains and controlled enzymatic depolymerization. Comparative analysis of wild-type xanthan and{Delta} gumI and{Delta} gumK variants enabled the unambiguous assignment of {beta}-mannose and glucuronic acid resonances, and, by extension, of the remaining sugars, supporting future structural studies of engineered xanthan variants. In addition, we investigated how side-chain composition affects xanthan properties by analyzing genetically modified variants lacking specific acetyl, pyruvyl, or sugar residues. Temperature-dependent 1H NMR determined order-disorder transition temperatures and revealed that removing pyruvate or negatively charged side-chain components increased thermal stability, whereas losing the terminal {beta}-mannose destabilized the ordered conformation. Together, these results establish a robust NMR assignment for xanthan and provide new insights into how individual side-chain substituents influence the structural stability of this polysaccharide, facilitating the rational characterization of engineered xanthan variants and structurally closely related polysaccharides.
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BibTeX
@misc{wegner2026assignment,
title = {{NMR assignment and functional characterization of biotechnologically modified xanthan}},
author = {J. Wegner and K. Johansen and P. Lanvers and M. Gansbiller and B. E. Christensen and J. Schmid and G. Courtade},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.28.762522},
url = {https://www.biorxiv.org/content/10.64898/2026.10.28.762522v1},
note = {CC BY-NC},
}
RIS
TY - UNPB
TI - NMR assignment and functional characterization of biotechnologically modified xanthan
AU - J. Wegner
AU - K. Johansen
AU - P. Lanvers
AU - M. Gansbiller
AU - B. E. Christensen
AU - J. Schmid
AU - G. Courtade
PY - 2026
DA - 2026/10/28
PB - bioRxiv
DO - 10.64898/2026.10.28.762522
UR - https://www.biorxiv.org/content/10.64898/2026.10.28.762522v1
AB - Xanthan gum is one of the most important industrial microbial polysaccharides, yet comprehensive molecular-level structural characterization remains limited because of its high molecular weight, conformational rigidity, and severe spectral overlap in nuclear magnetic resonance spectroscopy. Here, we present a near-complete 1H/13C NMR chemical shift assignment of the xanthan repeating unit by combining multidimensional NMR spectroscopy with targeted glycosyltransferase knockout strains and controlled enzymatic depolymerization. Comparative analysis of wild-type xanthan and{Delta} gumI and{Delta} gumK variants enabled the unambiguous assignment of {beta}-mannose and glucuronic acid resonances, and, by extension, of the remaining sugars, supporting future structural studies of engineered xanthan variants. In addition, we investigated how side-chain composition affects xanthan properties by analyzing genetically modified variants lacking specific acetyl, pyruvyl, or sugar residues. Temperature-dependent 1H NMR determined order-disorder transition temperatures and revealed that removing pyruvate or negatively charged side-chain components increased thermal stability, whereas losing the terminal {beta}-mannose destabilized the ordered conformation. Together, these results establish a robust NMR assignment for xanthan and provide new insights into how individual side-chain substituents influence the structural stability of this polysaccharide, facilitating the rational characterization of engineered xanthan variants and structurally closely related polysaccharides.
ER -