The infectious liver disease hepatitis C is caused by the small, enveloped, positive single-strand RNA hepatitis C virus (HCV). The HCV genome encodes for a single polyprotein precursor of ∼3010 amino acid residues. Host and cellular proteases co- and posttranslational process the precursor creating six nonstructural (NS) proteins and four structural components. Properly folded forms of the envelope proteins E1 and E2 form the associated E1-E2 complex. This complex represents a significant antigenic component at the viral surface that can interact with several target cell receptors. Extent and type of glycosylation is an important factor for virulence and escape from the immune system. Detailed characterization of the glycosylated sites is helpful for the understanding of different phenotypes as well as for the development of E1/E2-related treatments of HCV infection. Here, we have investigated in detail the O-linked glycosylation of the HCV envelope protein E2 expressed in and isolated from human embryonic kidney (HEK 293) cells. Using nano-liquid chromatography and tandem mass spectrometry approaches, we clearly have identified six residues for O-linked glycosylation within isolated glycopeptides (Ser393, Thr396, Ser401, Ser404, Thr473 and Thr518), carrying mainly Core 1 and Core 2 mucin-type structures. Based on our data, Thr385 is probably glycosylated as well. In addition, we could show that Ser479 within the hyper variable region (HVR) I is not O-glycosylated. For most of these sites, different degrees of microheterogeneity could be verified. Concerning HCV E2, this is the first case of experimentally proven O-linked glycosylation in detail via mass spectrometry.
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http://dx.doi.org/10.1093/glycob/cws171 | DOI Listing |
Org Lett
January 2025
Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Chemical Biology Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, People's Republic of China.
We present a versatile palladium-catalyzed glycosylation platform that enables facile access to structurally diverse N-O-linked glycosides with constantly excellent regio- and stereoselectivities. Importantly, this approach offers a broad substrate scope, low catalyst loadings, and outstanding chemoselectivity, allowing for the selective reaction of oximes/hydroximic acids over hydroxyl groups that would otherwise pose challenges in conventional glycosylation methods. The synthetic utility of this method is further exemplified through a range of synthetic transformations and late-stage modification of bioactive molecules.
View Article and Find Full Text PDFViruses
December 2024
Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, 413 46 Gothenburg, Sweden.
The tick-borne encephalitis virus is a pathogen endemic to northern Europe and Asia, transmitted through bites from infected ticks. It is a member of the family and possesses a positive-sense, single-stranded RNA genome encoding a polypeptide that is processed into seven non-structural and three structural proteins, including the envelope (E) protein. The glycosylation of the E protein, involving a single N-linked glycan at position N154, plays a critical role in viral infectivity and pathogenesis.
View Article and Find Full Text PDFThe apolipoprotein E ( ) ε4 allele is the strongest genetic risk factor for Alzheimer's disease (AD). ApoE is glycosylated with an O-linked Core-1 sialylated glycan at several sites, yet the impact and function of this glycosylation on AD biomarkers remains unclear. We examined apoE glycosylation in a cohort of cerebrospinal fluid (CSF, n=181) and plasma (n= 178) samples from the Alzheimer's Disease Neuroimaging Initiative (ADNI) stratified into 4 groups: cognitively normal (CN), Mild Cognitive Impairment (MCI), progressors and non-progressors based on delayed word recall performance over 4 years.
View Article and Find Full Text PDFCell Biochem Biophys
January 2025
Department of Obstetrics, Women and Children's Hospital, School of Medicine, Xiamen University, Xiamen, 361003, China.
O-linked N-acetylglucosamine transferase (OGT)-catalyzed O-linked N-acetylglucosamine glycosylation (O-GlcNAcylation) is closely associated with diabetes progression. This study aims to investigate the mechanism of OGT in regulating endothelial dysfunction in gestational diabetes mellitus (GDM). Expressions of OGT, O-linked N-acetylglucosamine (O-GlcNAc), enhancer of zeste homolog 2 (EZH2), and HEK27me3 in human umbilical vein endothelial cells (HUVECs) and GDM-derived HUVECs (GDM-HUVECs) were assessed by western blot.
View Article and Find Full Text PDFPLoS One
December 2024
Department of Zoology, Lahore College for Women University, Lahore, Pakistan.
Protein glycosylation, a vital post-translational modification, is pivotal in various biological processes and disease pathogenesis. Computational approaches, including protein language models and machine learning algorithms, have emerged as valuable tools for predicting O-GlcNAc sites, reducing experimental costs, and enhancing efficiency. However, the literature has not reported the prediction of O-GlcNAc sites through the evolutionary scale model (ESM).
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