Exploiting thioether reactivity to label mycobacterial glycans
Name
smelyansky-et-al-2025-exploiting-thioether-reactivity-to-label-mycobacterial-glycans.pdf
Description
Published version
Size
1.18 MB
Format
Adobe PDF
Checksum (MD5)
0cb9f2c12461731488020289cf5a2ec7
Author(s)
Smelyansky, Stephanie R
Ma, Chi-Wang
Marando, Victoria M
Babunovic, Gregory H
Lee, So Young
Bryson, Bryan D
Kiessling, Laura L
Date Issued
May 5, 2025
Journal
Proceedings of the National Academy of Sciences
Publisher
National Academy of Sciences
Citation
S.R. Smelyansky,C. Ma,V.M. Marando,G.H. Babunovic,S.Y. Lee,B.D. Bryson, & L.L. Kiessling, Exploiting thioether reactivity to label mycobacterial glycans, Proc. Natl. Acad. Sci. U.S.A. 122 (19) e2422185122, (2025).
Version
Final published version
Abstract
Mycobacterium tuberculosis (Mtb) is a leading cause of death worldwide. Mtb cell envelope glycans are potent virulence factors that play key roles in mediating infection of host tissues and modulating the host immune response. However, there are few ways to site-selectively modify and label these or any glycans to study their functions in disease. This gap arises because glycans generally lack functional groups amenable to bioconjugation strategies. Methylthioxylofuranose (MTX), a rare monosaccharide in select pathogenic mycobacteria, is an exception. MTX is appended to mannose-capped lipoarabinomannan (ManLAM), an antigenic glycolipid in the Mtb cell envelope implicated in downregulating the host immune system during infection. MTX is unique not only in its prevalence but also in its functionality—it contains a thioether not present in other glycans. We envisioned exploiting the MTX thioether to selectively label ManLAM with an oxaziridine probe. Here, we show that MTX-containing glycans can be labeled selectively in the test tube and live cells, highlighting the reactivity and accessibility of this motif. Our approach labels ManLAM efficiently despite the presence of protein methionine residues and can distinguish between different mycobacterial species. Using an oxaziridine equipped with a reporter, we could visualize ManLAM localization in live cells and a macrophage infection model, highlighting the stability of the label and the cell envelope in this environment. These studies will enable investigations of dynamic changes in a critical Mtb cell envelope component during infection. Moreover, the selective reactivity of thioethers can be leveraged to expand the repertoire of glycan bioconjugation strategies.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
Ragon Institute of MGH, MIT and Harvard
Massachusetts Institute of Technology. Department of Biological Engineering
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Creative Commons Attribution-NonCommercial-NoDerivatives
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DOI of Published Version
https://doi.org/10.1073/pnas.2422185122
