N-glycosylation modulates enzymatic activity of Trypanosoma congolense trans-sialidase

Trypanosomes cause the devastating disease trypanosomiasis, in which the action of trans-sialidase (TS) enzymes harbored on their surface is a key virulence factor. TS enzymes are N-glycosylated, but the biological functions of their glycans have remained elusive. In this study, we investigated the...

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Published in:The Journal of biological chemistry 2022-10, Vol.298 (10), p.102403-102403, Article 102403
Main Authors: Rosenau, Jana, Grothaus, Isabell Louise, Yang, Yikun, Kumar, Nilima Dinesh, Ciacchi, Lucio Colombi, Kelm, Sørge, Waespy, Mario
Format: Article
Language:English
Subjects:
Animals
CHO Cells
Cricetinae
Cricetulus
enzyme kinetics
Glycoproteins - metabolism
Glycosylation
mass spectrometry
molecular dynamics
N-glycosylation
Neuraminidase - metabolism
Polysaccharides - metabolism
protein–glycan interactions
proteoglycan
trans-sialidases
trypanosoma
Trypanosoma congolense - enzymology
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Summary:Trypanosomes cause the devastating disease trypanosomiasis, in which the action of trans-sialidase (TS) enzymes harbored on their surface is a key virulence factor. TS enzymes are N-glycosylated, but the biological functions of their glycans have remained elusive. In this study, we investigated the influence of N-glycans on the enzymatic activity and structural stability of TconTS1, a recombinant TS from the African parasite Trypanosoma congolense. We expressed the enzyme in Chinese hamster ovary Lec1 cells, which produce high-mannose type N-glycans similar to the TS N-glycosylation pattern in vivo. Our MALDI-TOF mass spectrometry data revealed that up to eight putative N-glycosylation sites were glycosylated. In addition, we determined that N-glycan removal via endoglycosidase Hf treatment of TconTS1 led to a decrease in substrate affinity relative to the untreated enzyme but had no impact on the conversion rate. Furthermore, we observed no changes in secondary structure elements of hypoglycosylated TconTS1 in CD experiments. Finally, our molecular dynamics simulations provided evidence for interactions between monosaccharide units of the highly flexible N-glycans and some conserved amino acids located at the catalytic site. These interactions led to conformational changes, possibly enhancing substrate accessibility and enzyme–substrate complex stability. The here-observed modulation of catalytic activity via N-glycans represents a so-far-unknown structure–function relationship potentially inherent in several members of the TS enzyme family.
ISSN:0021-9258
1083-351X
DOI:10.1016/j.jbc.2022.102403