Biology subjects

Di Vagno, L.

Publications and source records attributed to Di Vagno, L..

4 recordsLinked to original sources

bioRxiv2026

An in vivo chemical genetic approach for targeted glycoproteome analysis in Drosophila melanogaster

Glycans impact every aspect of physiology. Despite the rapid increase in relevance and translational potential, there remains a lack of tools for studying glycosylation in vivo. Here, we present FlyMOE, a chemical-genetic platform for targeted glycoprotein profiling in Drosophila melanogaster. Transgenic flies are equipped with biosynthetic capabilities to install bioorthogonally-tagged monosaccharides into the cellular glycoproteome. The genetic tractability of Drosophila allows for versatile application based on developmental stages, genetic drivers and glycosyltransferase enzymes. We employ FlyMOE to create an overview of the glycoproteome of Drosophila tissues and embryos based on mass spectrometry glycoproteomics, and investigate the substrates of individual members of the PGANT glycosyltransferase family in vivo. FlyMOE will allow the detailed investigation of the glycoproteome in Drosophila and similarly genetically modifiable in vivo model systems.

bioengineering↗

bioRxiv2024

A candidate reference method for the quantification of α-synuclein in cerebrospinal fluid using an SI traceable primary calibrator and multiple reaction monitoring

Objectives-synuclein aggregation is an indicator of neurodegenerative diseases such as Parkinsons disease (PD) and recent advances have suggested that this protein could serve as a potential biomarker. It has been indicated that soluble and oligomeric -synuclein in biological fluids could have diagnostic applications for PD. Clinical laboratories currently rely on antibody-based assays to detect -synuclein. These assays have limited specificity, low sensitivity and poor inter-lab reproducibility, which prevents the validation of -synuclein as a biomarkers. This study aims to fill the unmet need for the standardisation of clinical measurements for -synuclein. MethodsWe report the first candidate reference method for -synuclein, using an SI traceable primary calibrator for -synuclein and isotope dilution mass spectrometry. The primary calibrator was traceably quantified utilising a combination of amino acid analysis and nuclear magnetic resonance. A targeted sample clean-up procedure involving a non-denaturing Lys-C digestion and solid-phase extraction allowed for the sensitive detection of multiple proteotypic -synuclein peptides in cerebrospinal fluid (CSF) samples. ResultsThe candidate reference method procedure showed linearity across three orders of magnitude, covering the physiological levels of -synuclein in CSF (LOQ = 0.1 ng/g). The method was used to quantify a cohort of CSF samples and the measurements were correlated with immunoassay-based quantifications. ConclusionsThe SI traceable quantification of -synuclein in complex biological matrices means that the role of this protein can be further elucidated in synucleinopathies. This candidate reference method would lead to the harmonisation of -synuclein measurements, which may allow for development of high throughput clinical tests.

biochemistry↗

bioRxiv2023

Xylosyltransferase Bump-and-hole Engineering to Chemically Manipulate Proteoglycans in Mammalian Cells

Mammalian cells orchestrate signalling through interaction events on their surfaces. Proteoglycans are an intricate part of these interactions, carrying large glycosaminoglycan polysaccharides that recruit signalling molecules. Despite their importance in development, cancer and neurobiology, a relatively small number of proteoglycans have been identified. In addition to the complexity of glycan extension, biosynthetic redundancy in the first protein glycosylation step by two xylosyltransferase isoenzymes XT1 and XT2 complicates annotation of proteoglycans. Here, we develop a chemical genetic strategy that manipulates the glycan attachment site of cellular proteoglycans. By employing a tactic termed bump- and-hole engineering, we engineer the two isoenzymes XT1 and XT2 to specifically transfer a chemically modified xylose analogue to target proteins. The chemical modification contains a bioorthogonal tag, allowing the ability to visualise and profile target proteins modified by both transferases in mammalian cells. The versatility of our approach allows pinpointing glycosylation sites by tandem mass spectrometry, and exploiting the chemical handle to manufacture proteoglycans with defined GAG chains for cellular applications. Engineered XT enzymes permit a view into proteoglycan biology that is orthogonal to conventional techniques in biochemistry.

biochemistry↗

bioRxiv2022

O-Linked Sialoglycans Modulate the Proteolysis of SARS-CoV-2 Spike and Contribute to the Mutational Trajectory in Variants of Concern

The emergence of a polybasic cleavage motif for the protease furin in the SARS-CoV-2 spike protein has been established as a major factor for enhanced viral transmission in humans. The peptide region N-terminal to that motif is extensively mutated in major variants of concern including Alpha, Delta and Omicron. Besides furin, spike proteins from these variants appear to rely on other proteases for maturation, including TMPRSS2 that may share the same cleavage motif. Glycans found near the cleavage site have raised questions about proteolytic processing and the consequences of variant-borne mutations. Here, with a suite of chemical tools, we establish O-linked glycosylation as a major determinant of SARS-CoV-2 spike cleavage by the host proteases furin and TMPRSS2, and as a likely driving force for the emergence of common mutations in variants of concern. We provide direct evidence that the glycosyltransferase GalNAc-T1 primes glycosylation at Thr678 in the living cell, and this glycosylation event is suppressed by many, but not all variant mutations. A novel strategy for rapid bioorthogonal modification of Thr678-containing glycopeptides revealed that introduction of a negative charge completely abrogates furin activity. In a panel of synthetic glycopeptides containing elaborated O-glycans, we found that the sole incorporation of N-acetylgalactosamine did not substantially impact furin activity, but the presence of sialic acid in elaborated O-glycans reduced furin rate by up to 65%. Similarly, O-glycosylation with a sialylated trisaccharide had a negative impact on spike cleavage by TMPRSS2. With a chemistry-centered approach, we firmly establish O-glycosylation as a major determinant of spike maturation and propose that a disruption of O-GalNAc glycosylation is a substantial driving force for the evolution of variants of concern. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=89 SRC="FIGDIR/small/508093v3_ufig1.gif" ALT="Figure 1"> View larger version (26K): org.highwire.dtl.DTLVardef@71b54eorg.highwire.dtl.DTLVardef@1361b4aorg.highwire.dtl.DTLVardef@139bdd9org.highwire.dtl.DTLVardef@1df192b_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗