Antibody N-linked glycosylation profiling with PEAKS GlycanFinder
Ontology highlight
ABSTRACT: We conducted a new mass spectrometry experiment for antibody N-linked glycosylation profiling that could distinguish isomeric peptides and glycans in four immunoglobulin G subclasses.
Project description:Real-time database searching allows for simpler and automated proteomics workflows as it eliminates technical bottlenecks in high throughput experiments. Most importantly, it enables results dependent acquisition (RDA) where search results can be used to guide data acquisition during acquisition. This is especially beneficial for glycoproteomics since the wide range of physicochemical properties of glycopeptides lead to a wide range of optimal acquisition parameters. We established here the GlycoPaSER prototype by extending the Parallel Search Engine in Real-time (PaSER) functionality for real-time glycopeptide identification from fragmentation spectra. Glycopeptide fragmentation spectra were decomposed into peptide- and glycan-moiety spectra using common N-glycan fragments. Each moiety was subsequently identified by a specialized algorithm running in real-time. GlycoPaSER can keep up with the rate of data acquisition for real-time analysis with similar performance to other glycoproteomics software and produces results that are in line with literature reference data. The GlycoPaSER prototype presented here provides the first proof-of-concept for real-time glycopeptide identification that unlocks future development of RDA technology to transcend data acquisition.
Project description:A microfluidics technology was implemented to the immunoaffinity purification process of MHC peptides in Ligandomics/Immunopeptidomics. The thus purified HLA peptides were analysed by LCMS with the nanoElute LC and TimsTOF Pro Mass Spectrometer from Bruker. The aim of the microfluidics implementation was to improve the sensitivity and robustness while also reducing antibody and other material requirements in the immunoaffinity purification protocol.
Project description:In this study we demonstrate the effect of oncolytic adenoviruses armed with CXCL9, CXCL10 and IL-15 to infect cancer cells, secrete the encoded protein and drive gradient-dependent T-cell attraction. Our in vivo validation demonstrated an increased intratumoral CD4+ and CD8+ T-cell infiltration following treatment with armed viruses compared to control groups. Finally, RCC cells were screened for tumor-specific peptides to validate their immunogenicity in a (personalized) oncolytic cancer vaccine approach, previously referred to as PeptiCRAd.
Project description:We employed PeptiCHIP Immunopeptidomics to profile tumor associated antigens (TAA) actively targeted by tumor specific T cells by exploiting the trogocytosis effect, whereby antigen presenting cells (APCs) nibble portions of the cognate T cell containing the TCR. The antigen presenting cells were then processed by Immunoaffinity purification by peptiCHIP to identify the relevant HLA-I peptides by LCMS on the Bruker Tims TOF Pro instrument.
Project description:During collagen biosynthesis, lysine residues undergo extensive post-translational modifications through the alternate action of two distinct metal ion-dependent enzyme families (i.e., LH/PLODs and GLT25D/COLGALT), ultimately producing the highly conserved alpha-(1,2)-glucosyl-beta-(1,2)-galactosyl-5-hydroxylysine pattern. Malfunctions in these enzymes are linked to developmental pathologies and extracellular matrix alterations associated to enhanced aggressiveness of solid tumors. Here, we characterized human GLT25D1/COLGALT1, revealing an elongated head-to-head homodimeric assembly. Each monomer encompasses two domains (GT1 and GT2), both unexpectedly capable of binding metal ion cofactors and UDP-alpha-galactose donor substrates, resulting in four candidate catalytic sites per dimer. We identified the catalytic site in GT2, featuring an unusual Glu-Asp-Asp motif critical for Mn2+ binding, ruling out direct catalytic roles for the GT1 domain, but showing that the unexpectedly bound Ca2+ and UDP-alpha-galactose cofactors are critical for folding stability. Dimerization was not essential for GLT25D1/COLGALT1 activity, but rather a hallmark for multi-enzyme assembly interactions and/or collagen substrate recognition.
Project description:SUMOylation is a post-translational modification involving the addition of SUMO isoforms to target proteins and plays a role in various biological processes, including neurodegenerative diseases and ocular pathologies. This study investigates the interaction between SUMO-2 and amyloid (Aβ) peptides, key contributors to Alzheimer’s disease, using techniques like cross-linking mass spectrometry, surface plasmon resonance and biolayer interferometry. The results show that Aβ1-40 and Aβ1-42 bind more strongly to SUMO-2 than to ubiquitin, with binding driven by specific hydrogen bonds and hydrophobic interactions. SUMO-2 was found to inhibit the conversion of Aβ into β-sheet structures and impede Aβ aggregation. Notably, Aβ competes with SUMO-2’s canonical substrates for binding, completely hindering SUMOylation reactions in vitro. Identifying SUMO-2/Aβ1-42 adducts in cellular extracts and live cells further highlights the biological significance of these interactions. Overall, the findings indicate that Aβ peptides impair SUMO-2 function, pointing to the necessity for more research on the implications of SUMOylation in Alzheimer's disease.
Project description:While it is known that endocannabinoids (eCB) modulate multiple neuronal functions, the molecular mechanism governing their release and transport remains elusive. Here, we propose an “on demand release” model, wherein the formation of microvesicles, a specific group of extracellular vesicles (EVs) containing the eCB, 2-arachidonoylglycerol (2-AG), is the rate-limiting step. A co31 culture model system that combines a reporter cell line expressing the fluorescent eCB sensor,GRABeCB2.0, and neuronal cells revealed that neurons release EVs containing 2-AG, but not anandamide, in a stimulus-dependent process regulated by PKC, DAGL, Arf6, and which was sensitive to inhibitors of eCB facilitated diffusion. A vesicle contained approximately 2000 2-AG molecules. Accordingly, hippocampal eCB-mediated synaptic plasticity was modulated by Arf6 and transport inhibitors. This “on demand release” model, supported by mathematical analysis, offers a cohesive framework for understanding eCB signaling at the molecular level and suggests that microvesicles carrying signaling lipids regulate neuronal functions in parallel to canonical synaptic vesicles. To show the identity and purity of the EVs isolated in this study, the proteome of the EVs and their parental cells were analyzed by LC-MS/MS
Project description:We used a streamlined pipeline for the generation of personalized cancer vaccines starting from the isolation and selection of the most immunogenic peptide candidates expressed on the tumour cells and ending in the generation of efficient therapeutic oncolytic cancer vaccines. We used MHC-I immunoaffinity purification in a murine colon tumor model from CT26 cells. The selection of the target candidates was then based on two separate approaches: RNAseq analysis and HEX software.
Project description:Immunoaffinity purification was performed on human mesothelioma cell lines NCI-H2452, NCI-H28, MSTO-211H and JL1, on murine mesothelioma cell line AB12, as well as on mesothelioma samples from two patients (including tumor and benign tissues). Thereafter Immunopeptidomics by Mass Spectrometry on a Tims TOF Pro revealed the MHC peptide landscape of mesothelioma.
Project description:α-Synuclein (α-syn) is an intrinsically disordered protein (IDP) that undergoes liquid-liquid phase separation (LLPS), fibrillation, and forms insoluble intracellular Lewy’s bodies in neurons, which are the hallmark of Parkinson’s Disease (PD). Neurotoxicity precedes the formation of aggregates and is probably related to LLPS of α-syn in the cell. The molecular mechanisms underlying the early stages of LLPS are still elusive. To obtain structural insights into α-syn upon LLPS, we take advantage of cross-linking/mass spectrometry (XL-MS) and introduced an innovative new approach, termed COMPASS (COMPetitive PAiring StatisticS). COMPASS unravels transient interactions between α-syn molecules in liquid droplets to derive structural information of α-syn upon LLPS. In this work, we show that the conformational ensemble of α-syn shifts towards more elongated conformational states upon LLPS. We obtain insights into the critical initial stages of PD and establish a novel mass spectrometry-based approach that will aid to solve open questions in LLPS structural biology.