Trypanosoma c ruzi Trans-sialidase Operates through a Covalent Sialyl−Enzyme Intermediate: Tyrosine Is the Catalytic Nucleophile
Abstract
Modified sialic acid substrates have been used to label Trypanosoma cruzi trans-sialidase, demonstrating that the enzyme catalyses the transfer of sialic acid through a covalent glycosyl-enzyme intermediate, a mechanism common to most retaining glycosidases. Peptic digestion of labeled protein, followed by LC-MS/MS analysis of the digest, identified Tyr342 as the catalytic nucleophile. This is the first such example of a retaining glycosidase utilizing an aryl glycoside intermediate. It is suggested that this alternative choice of nucleophile is a consequence of the chemical nature of sialic acid. A Tyr/Glu couple is invoked to relay charge from a remote glutamic acid, thereby avoiding electrostatic repulsion with the sialic acid carboxylate group.
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Sialidase catalysis proceeds via nucleophilic Tyr364 assisted by Glu258, protonation by Asp97, a covalent tyrosine-sialate intermediate, and hydrolysis by water.
“The nucleophilic Tyr364, assisted by Glu258, displaces the glycan leaving group, which is protonated by Asp97, resulting in a covalent tyrosine-sialate intermediate. This adduct is then hydrolyzed by water, again with the help of Asp97.”
From Structure of the immunoregulatory sialidase NEU1 (2023) · cites this paper as [70]
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- Authors
- Watts, A. G., Damager, I., Amaya, M. L., Buschiazzo, A., Alzari, P., Frasch, A. C., & Withers, S. G.
- Affiliations
- University of British Columbia (CA)
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, B.C., Canada V6T 1Z1, Unite de Biochemie Structurale, Institut Pasteur, 25 rue du Dr. Roux, 75724 Paris, France, and Instituto de Investigaciones Biotechnologicas-Universidad Nacional de San Martin, CC 30, 1650 San Martin, Argentina
- ORCID
- Venue
- Journal of the American Chemical Society
- Publisher
- American Chemical Society (ACS)
- Published
- 2003-05-30
- Volume
- 125
- Issue
- 25
- Pages
- 7532-7533
- ISSN
- 0002-7863 (ISSN-L)
- 1520-5126
- OpenAlex
- W1982867767
- Cited by
- 211
- References
- 0
- Citations by year
- 2026: 6 · 2025: 7 · 2024: 7 · 2023: 3 · 2022: 7 · 2021: 3 · 2020: 6 · 2019: 12 · 2018: 12 · 2017: 6 · 2016: 5 · 2015: 10 · 2014: 15 · 2013: 12 · 2012: 8
- FWCI
- 4.60
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Journal of the American Chemical Society (publishedVersion)
- PubMed (publishedVersion)
- HAL (submittedVersion)
- Topics
- Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Glycosylation and Glycoproteins Research
- Physical Sciences › Chemistry › Organic Chemistry › Carbohydrate Chemistry and Synthesis
- Health Sciences › Medicine › Epidemiology › Trypanosoma species research and implications
- Keywords
- Trypanosoma cruzi, trans-sialidase, sialic acid transfer, electrostatic repulsion, Chagas disease
- MeSH terms
- Animals, Catalysis, Enzyme Activation, Glycoproteins, Kinetics, Neuraminidase, Trypanosoma cruzi, Tyrosine, Spectrometry, Mass, Electrospray Ionization
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