Biology subjects

Heck, A. J. R.

Publications and source records attributed to Heck, A. J. R..

At least 19 recordsLinked to original sources

bioRxiv2026

IgG4 antibody repertoire diversity is stable over several years in health and autoimmune disease

Despite its relative anti-inflammatory nature, IgG4 is involved in a variety of pathological conditions such as autoimmune disease and cancer. To investigate whether the IgG4 repertoire presents any abnormalities in diseases where IgG4 autoantibodies predominate, we charted longitudinal IgG4 repertoires in health, in an IgG4-mediated autoimmune disease (AID; muscle-specific kinase myasthenia gravis (MuSK MG)), and in IgG1/IgG3 mediated AIDs (acetylcholine receptor (AChR) MG and Lambert-Eaton myasthenic syndrome (LEMS). In total, we assessed 218 samples of 69 donors using mass spectrometry-based antibody repertoire analysis, covering a timespan of up to eight years. Despite being superficially inconspicuous in clonal diversity and abundances, we detected a slightly elevated number of IgG4 clones in MuSK MG patients compared to healthy donors. Notably, this observation did not coincide with drastic repertoire changes during treatment, suggesting that a large portion of the IgG4 repertoire is not significantly affected by common MuSK MG treatment regimens. Comparing the IgG4 antibody repertoires of all donors, we found that they were exceptionally unique for each individual. Against what would be expected in the case of a constantly adapting antibody repertoire, a large portion of the IgG4 clones remained stable without any further maturation. This observation even extended to patients receiving B cell depleting or IgG modulating treatments. Our findings suggest that a dominating fraction of the IgG4 pool may be produced by long-lived plasma cells, which are unaffected by disease or medical interventions.

immunology↗

bioRxiv2026

Disentangling maternal pregnancy and fetal-specific plasma signatures through integrated proteomics and site-specific N-glycoproteomics

During pregnancy, mother and fetus co-exist albeit as two physiologically distinct individuals, connected through the placenta and the umbilical cord. This connection allows for the exchange of vital substances, while individual blood homeostasis remains intact. We hypothesized that comparing maternal and cord plasma (N-glyco)proteomes would provide insights into the biological communication and unique physiological state of each individual. As comparing only matched maternal and umbilical cord blood plasma misses a crucial identifier in determining whether observed changes are related to infancy, pregnancy or both, we designed a triad study by adding a non-pregnant women control group. This allowed us to distinguish pregnancy-specific proteins and their potentially altered N-glycosylation from those in infancy. We found that the fetus and mother have distinct proteomes, N-glycoproteoforms and alternative complement regulation. Moreover, we observed that pregnancy in women led to specific N-glycosylation changes on a select set of primarily HDL-associated and acute-phase proteins. Lastly, our data provide evidence for an early fetal development of the humoral immune system as especially fetal IgM displayed distinctive N-glycosylation signatures.

developmental biology↗

bioRxiv2026

Mycoplasma immunoglobulin binding protein universally binds human antibodies, thereby reducing Fab arm flexibility and displacing antigens in immune complexes

Mycoplasma immunoglobulin binding (MIB) protein plays a key role in immune evasion across several Mycoplasma species. MIB tightly interacts with the Fab domain of immunoglobulin G, inducing conformational changes that disrupt the antigen-binding site. Here, we reveal that MIB binds strongly and universally to all major isotypes and subclasses of human antibodies and can thus serve as a bait protein to efficiently deplete antibodies from serum. Our results demonstrate strong interactions between MIB and a diverse set of both recombinant monoclonal and endogenous polyclonal antibodies, the latter purified from serum or colostrum. All antibodies, including IgG and IgA monomers, J-chain coupled IgA dimers, and IgM pentamers, consistently bind two copies of MIB per antibody protomer. Using cross-linking mass spectrometry, we pinpoint that antibody-MIB interactions involve conserved regions of the variable and constant antibody domains, independent of isotype. Furthermore, we demonstrate that MIB not only disrupts the Fab-antigen interaction but also restricts Fab flexibility, as visualized by atomic force microscopy. Conversely, MIB does not affect Fc-mediated protein interactions, as exemplified by the successful reconstitution of a 36-subunit immune complex, (IgG)6-(MIB)12-C1q.

biochemistry↗

bioRxiv2026

Direct serological antibody discovery by integrative proteomics yields potent neutralizers overlooked by single-cell BCR sequencing

Human antibody discovery relies on accessing in vivo-matured repertoires, yet conventional single-cell B cell receptor sequencing (scBCR-seq) often overlooks the most relevant, functional antibodies secreted by plasma cells. Here, we introduce AbDirect, a protein-centric discovery platform that obtains antibody sequences directly from small-volume biofluids. In this proof-of-concept, we apply AbDirect to potent COVID-19 plasma from which an early-pandemic scBCR-seq study did not identify neutralizers. Upfront reactivity screening of anti-SARS-CoV-2 spike protein repertoires revealed diverse clonal profiles with distinct cross-reactivity and subunit specificity. Targeted de novo sequencing via standalone integrative proteomics yielded 14 IgG1 and 4 IgA1 clones that diverged markedly from peripheral B cell counterparts in germline usage and phylogeny, indicating distinct immunological compartments. Validation via recombinant mAbs demonstrated superior binding and highly potent neutralization for multiple sequenced clones (three with IC50 [≤]1.4 nM). AbDirect thus yielded potent antibodies overlooked by scBCR-seq, demonstrating serological discovery as a powerful complementary approach for uncovering functional repertoires that may be inaccessible to cell-based methods.

immunology↗

bioRxiv2026

Host cell remodeling via cyclin dependent kinases drives Ebola virus replication and transcription

Ebola virus (EBOV) causes re-emerging outbreaks of viral hemorrhagic fever with high case-fatality rates. As a negative-sense single stranded RNA virus, EBOV depends on its RNA-dependent RNA polymerase (L protein) to transcribe and replicate the viral genome. This takes place in cytoplasmic inclusion bodies that form following host cell remodeling involving yet unknown signaling pathways. Here, using mass spectrometry-based (phospho-)proteomics, we profiled global protein abundance and site-specific phosphorylation in HEK293T cells expressing an EBOV minigenome system. Our data reveal EBOV-induced rewiring of the host proteome and phosphorylation signaling landscape, including perturbations in cell cycle control, cytoskeletal organization, innate immune regulation, and DNA damage response. Kinase network analysis revealed that Hippo pathway kinases and especially cyclin dependent kinases like CDK2 are central drivers of EBOV replication and transcription. The functional necessity of these signaling pathways is demonstrated via inhibition of CDK family kinases with small molecule inhibitors, which halted EBOV minigenome replication and transcription when administered in the low micromolar range, demonstrating that these pathways represent putative antiviral targets.

molecular biology↗

bioRxiv2026

Expanding Glycopeptide Identification with Match-Between-Glycans in FragPipe

Glycosylation is one of the most important, but also most complex, post-translational modifications of proteins, playing a pivotal role in various pathological processes. Mass spectrometry-based large-scale glycoproteomics analysis offers a powerful approach to explore the fundamental roles of glycosylation in both physiological and pathological contexts. Traditionally, DDA glycopeptide assignment relies on information-dense MS2 spectra, containing sufficient fragmentation information to identify both the peptide and glycan moieties. Achieving this fragmentation can be difficult, especially for low-abundant glycopeptides and/or large, complex glycans. These glycopeptides are often not assigned using current data analysis software, yet they can be of biological relevance. Here, we introduce a method called match-between-glycans (MBG), which expands glycopeptide identification while maintaining the existing glycoproteome analysis workflow. MBG enables expanding the set of identified glycopeptides to include those without MS2 spectra, or with lower quality MS2 spectra, by looking for MS1 signals displaced from other identified glycopeptides by one or multiple monosaccharide unit(s). MBG can also identify glycans not included in the glycan database, such as those containing adducts or modifications, allowing these glycans to be recovered without a drastic expansion of the search space. Combined with target-decoy FDR control, we show this method is capable of accurately expanding glycopeptide identifications and providing a more complete quantitative profile of glycosylation at each glycosite. MBG is fully integrated into the glycoproteomics workflows in FragPipe, allowing seamless, one-click operation.

bioinformatics↗

bioRxiv2025

Uncovering the link between ATP synthase and the TCA cycle by crosslinking mass spectrometry

Mitochondrial oxidative phosphorylation (OXPHOS) comprises a series of multi-subunit protein complexes that operate in coordination with the tricarboxylic acid (TCA) cycle to generate ATP. Although these systems are metabolically interconnected, complex II is generally regarded as the only direct structural link between the OXPHOS and TCA cycle. Here, we combine in-solution crosslinking mass-spectrometry (XL-MS), quantitative proteomics, and blue native PAGE (BN-PAGE) to explore how ATP synthase (complex V) integrates within the mitochondrial metabolic network under physiological and pathological conditions. We demonstrate that in murine wild-type hearts, the F1 catalytic head of ATP synthase forms extensive contacts with TCA cycle enzymes, establishing a previously unanticipated link between the OXPHOS and central carbon metabolism. We also found that under mitochondrial dysfunction, in this case LRPPRC-deficient hearts, where defective mitochondrial DNA gene expression destabilizes ATP synthase, these interactions become strengthened. Moreover, ATP synthase dysfunction promotes binding of the ATPase inhibitory factor 1 (ATIF1) to the F1 head via its N-terminal inhibitory region, shifting the ATP synthase toward an energy-preserving state. Together, our findings show that ATP synthase deficiency drives remodeling of the F1 interactome, revealing how mitochondrial structure and regulation adapt to preserve energy homeostasis under stress.

biochemistry↗

bioRxiv2025

Structural promiscuity in the human circulatory IgA1 clonal repertoire

Immunoglobulin A (IgA) is the most abundant antibody in humans, with high concentrations in both mucosae/secretions and circulation. While mucosal IgA has been studied extensively, characterization of human IgA in serum and its distinctive functions lags behind. Circulatory IgA is regularly assumed to be monomeric, despite some reports describing a minor population of J-chain-coupled dimers. Here, we first charted the compositional landscape of human serum IgA in individual healthy donors. In addition to the expected predominating monomers, we consistently observed J-coupled dimers, even representing [~]30% of one donors total serum IgA. To determine whether these structurally distinct populations were also clonally distinct, we employed mass spectrometry-based IgA1 clonal profiling in sera of two donors. Our data revealed the majority of IgA1 clones are present solely as monomers, with a smaller number exclusively dimeric. Strikingly, a third population of IgA1 clones is present in circulation as both monomers and J-coupled dimers. In fact, these shared, structurally-promiscuous IgA1 clones dominated both individuals serum IgA1 clonal repertoires. Our findings suggest likely every J+ IgA-secreting cell can co-produce monomers and J-coupled dimers, but what exactly determines this ratio requires further investigation. This finding is important, as IgA monomers and J-coupled dimers have distinct characteristics in antigen binding, receptor activation, and clearance from circulation, with several reports highlighting, for instance, the enhanced neutralization capacity of dimeric IgA. As we show here, the human immune system is not merely capable of producing both forms, but apparently prefers doing so in parallel. Significance StatementHuman immunoglobulin IgA occurs in diverse assemblies, mainly monomers (mIgA) and J-chain coupled dimers (dIgA). The general view is that these forms are produced at different sites, i.e., circulatory and mucosal, with the former assumed to represent mIgA. Inherently, it would not be expected that these populations have any overlap in their clonal repertoire. Here, we report the first analysis at the protein level of assembly-specific IgA1 clonal repertoires in sera of healthy individual donors. Strikingly, we find a substantial subset of clones that co-occur as both mIgA1 and dIgA1 assemblies, hinting at shared B-cell origins. This marks a paradigm shift in current understanding of human IgA, where these assemblies are classically viewed as structurally, functionally, and clonally distinct.

biochemistry↗

bioRxiv2025

Immunoglobulin sub-class levels define inter-donor plasma variability: a longitudinal dual-lab study

Advancements in mass spectrometry have transformed plasma proteomics, allowing for high-throughput analysis of large cohorts. This study utilized the TIMES cohort, consisting of 51 healthy participants monitored monthly over 12 months, to evaluate intra- and inter-individual variability in the plasma proteome. Approximately 600 samples were analyzed in two independent laboratories, revealing strong correlations despite methodological differences. The study focused on the stability of the plasma proteome within donors over a year, with larger differences observed between donors. A support vector machine model achieved a 98% median classification accuracy, confirming stable, donor-specific proteomic profiles. Immunoglobulins, often overlooked in plasma proteomics, were found to contribute significantly to donor-specific signatures, showing pronounced inter-individual variability but remarkable intra-donor stability. In contrast, C-reactive protein and other inflammation markers exhibited significant temporal fluctuations and donor-specific baseline levels. This inter-laboratory study highlights the importance of longitudinal sampling for biomarker discovery, the robustness of MS-based proteomic workflows, and provides new insights into immunoglobulin dynamics and variability in human plasma. Synopsis O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=65 SRC="FIGDIR/small/686385v1_ufig1.gif" ALT="Figure 1"> View larger version (19K): org.highwire.dtl.DTLVardef@1e7b501org.highwire.dtl.DTLVardef@11c85d7org.highwire.dtl.DTLVardef@1971a1dorg.highwire.dtl.DTLVardef@1338061_HPS_FORMAT_FIGEXP M_FIG C_FIG O_LILongitudinal analysis of individual plasma proteomes over a one-year period revealed low intra-individual variability albeit high inter-individual differences. C_LIO_LICross-site laboratory comparisons confirmed strong concordance in analytical performance and measurement consistency. C_LIO_LIConversion of relative protein intensities to absolute concentrations revealed immunoglobulin levels on par with established clinical reference ranges. C_LIO_LIDonors were distinguishable based on their unique plasma proteome. C_LIO_LIThe immunoglobulin sub-classes are key discriminators defining inter- and intra-donor variability C_LI

molecular biology↗

bioRxiv2025

Increased EThcD efficiency on the hybrid Orbitrap Excedion Pro Mass Analyzer extends the depth in identification and sequence coverage of HLA class I immunopeptidomes

Gaining a complete and unbiased understanding of the non-tryptic peptide repertoire presented by HLA-I complexes by LC-MS/MS is indispensable for therapy design for cancer, autoimmunity and infectious diseases. A serious concern in HLA peptide analysis is that the routinely used, collision-based fragmentation methods (CID/HCD) do not always render sufficiently informative MS2 spectra, whereby gaps in the fragmentation sequence coverage prevent unambiguous assignments. EThcD can be utilized to generate complementary ion series, i.e. b/y ions and c/z ions, resulting in richer, more informative MS2 spectra, thereby filling in the gaps. Here, we present data generated on a novel hybrid Orbitrap mass spectrometer, facilitating fast and efficient hybrid fragmentation due to the implementation of EThcD in the ion routing multipole. We hypothesized that this would enable more comprehensive and less error-prone analysis of immunopeptidomes at minimal costs in duty-cycle. First, we optimized ETD/EThcD methods using an elastase-digested cell lysate, as this contains peptides of similar length and charge distributions to immunopeptides. Next, we compared HCD and EThcD on immunopeptidomes originating from three cell lines with distinct HLA-I complexes that present peptides with varying physicochemical properties. We demonstrate that the new instrument not only enables efficient and fast ETD reactions, but when combined with collision-based supplemental activation, i.e. EThcD, also consistently increases the sequence coverage and identification of peptide sequences, otherwise missed by using solely HCD. We reveal several of the biochemical properties that make HLA peptides preferably identifiable by EThcD, with internal Arg residues being one of the most dominant determinants. Finally, we demonstrate the power of EThcD for the identification and localization of HLA peptides harboring post-translational modifications, focusing here on HLA Arg mono-/di-methylation. We foresee that this new instrument with efficient EThcD capabilities enhances not only immunopeptidomics analysis, but also analysis of peptides harboring post-translational modifications and de novo sequencing.

biochemistry↗

bioRxiv2025

Enhanced recognition of topoisomerase 1 upon DNA binding by a subset of anti-topoisomerase 1 autoantibodies in systemic sclerosis

ObjectivesSystemic sclerosis (SSc) is a deleterious disease. Its clinical management is complicated by strong interpatient heterogeneity. Progressive organ fibrosis is linked to autoantibodies against topoisomerase 1 (TOP1). Here, we hypothesized that the molecular interaction between anti-TOP1 autoantibodies (ATAs) and TOP1 could be a relevant determinant of SSc pathogenesis. DNA binding by TOP1 might affect its interaction with ATAs. Therefore, we studied the effect of DNA binding by TOP1 on ATA recognition. MethodsATA monoclonal antibodies (ATA mAbs) were generated from patient-derived TOP1-reactive B cells. Reactivity of ATA mAbs and antibodies in patient plasma towards TOP1 and TOP1-DNA cleavage complexes (TOP1cc) was determined by ELISA and mass photometry. Immunostimulatory properties of ATA mAbs in complex with TOP1/TOP1cc were assessed by stimulation of monocytic THP-1 cells. ResultsDNA binding by TOP1 differentially affected the recognition of TOP1 by ATA mAbs. A subset of mAbs showed enhanced binding to TOP1cc, whereas others recognized TOP1 and TOP1cc to a similar extent. ATAs with enhanced TOP1cc recognition were observed in plasma of ATA+ SSc patients and correlated with ATA levels and interstitial lung disease. These TOP1cc-enhanced ATAs variably affected the enzymatic function of TOP1 and circulated predominantly as IgG1 and IgM. The interaction of TOP1cc-enhanced ATA mAbs with TOP1cc strongly increased IL-8 production by THP-1 cells. ConclusionsThe differential recognition of TOP1 upon DNA binding by ATAs demonstrates heterogeneity in the ATA B cell response, possibly impacting on disease-relevant processes in severe SSc.

immunology↗

bioRxiv2025

Deep Coverage and Extended Sequence Reads Obtained with a Single Archaeal Protease Expedite de novo Protein Sequencing by Mass Spectrometry

The ability to sequence proteins without reliance on a genomic template defines a critical frontier in modern proteomics. This approach, known as de novo protein sequencing, is essential for applications such as antibody sequencing, microbiome proteomics, and antigen discovery, which require accurate reconstruction of peptide and protein sequences. While trypsin remains the gold-standard protease in proteomics, its restricted cleavage specificity limits peptide diversity. This constraint is especially problematic in antibody sequencing, where the functionally critical regions often lack canonical tryptic sites. As a result, exclusively trypsin-based approaches yield sparse reads, leading to sequence gaps. Multi-protease and hybrid-fragmentation strategies can improve the sequence coverage, but they add complexity, compromise scalability and reproducibility. Here, we explore two HyperThermoacidic Archaeal (HTA)-proteases as single-enzyme solutions for de novo antibody sequencing. Each HTA-protease generated about five times more unique peptide reads than trypsin or chymotrypsin, providing high redundancy across all CDRs. Combined with EAciD fragmentation on a ZenoTOF 7600 system, this approach enabled complete, unambiguous antibody sequencing. De novo analysis using PEAKS/DeepNovo and Stitch showed up to fourfold higher alignment scores and reduced the sequence errors within the HTA-generated data. Additionally, the HTA-EAciD approach offers short digestion times, eliminates extensive cleanup, and enables analysis in a single LC-MS/MS run. This streamlined, single-protease approach delivers therefore performance comparable to multi-enzyme workflows, offering a scalable and efficient strategy for de novo protein sequencing across diverse applications.

biochemistry↗

bioRxiv2025

Complete Enzyme Clustering Enhances Coenzyme Q Biosynthesisvia Substrate Channeling

Metabolons - transient assemblies of sequential metabolic enzymes - facilitate the reactions of multi-step metabolic pathways, yet, how they mechanistically bolster metabolic flux remains unknown. Here, we investigate the molecular determinants of metabolon formation in coenzyme Q (CoQ) biosynthesis using coarse-grained molecular dynamics simulations and biochemical experiments. We show that the COQ metabolon forms at the critical region of a phase transition, where both metabolon clustering and metabolic flux exhibit coordinated sigmoidal responses to changes in protein-protein interaction strength. These complete metabolons enable substrate channeling between sequential enzymes, leading to a crucial enhancement of CoQ production efficiency. Selectively disrupting protein-protein interactions and randomly shuffling the interaction network demonstrate that protein-proximity rather than fine structure of the metabolon clusters is imperative for substrate channeling. Grounded in both experiment and simulation, these findings provide a framework for understanding the organization and function of metabolons across diverse metabolic pathways.

biophysics↗

bioRxiv2025

Fab-arm exchange affects each and all endogenous serum IgG4 evenly

Antibodies are key molecular elements of the human immune system and account for an increasingly large proportion of therapeutics. Next to the well-studied and explored IgG1, several other classes (e.g. IgA, IgM) and sub-classes (e.g., IgG2, IgG3 and IgG4) exist in humans. In particular IgG4 is worth a closer examination as it has unique natural properties and is regularly used as a scaffold in biologicals. IgG4 stands out from the other IgG by its ability to dissociate and form two half-molecules which can interchange with those of other clones to form novel bivalent antibodies. Detailed analysis of endogenous IgG4 so far has been hampered by a lack of analytical methods to dissect and analyze IgG4 molecules with clonal resolution. Here, we present an LC-MS-based approach enabling the analysis of IgG4 repertoires with clonal resolution, which we used to monitor endogenous serum IgG4 repertoires from seven healthy donors. Most strikingly, our data reveal the combinatorial explosion in diversity of the serum IgG4 clonal repertoire. This phenomenon is explained by the stochastic behavior of Fab-arm exchange, making virtually each IgG4 molecule in serum bispecific. Although the endogenous IgG4 clonal repertoire is therefore extremely diverse, we demonstrate that this IgG4 repertoire persists over time within an individual healthy donor for more than one year. This newly established method now enables repertoire analysis for IgG4, which plays a critical role in a plethora of disease settings including allergy, autoimmunity and vaccination.

biochemistry↗

bioRxiv2025

Breaking barriers in the sensitive and accurate mass determination of large DNA plasmids by mass photometry

DNA plasmids (pDNA) are essential for gene cloning and protein expression, whereby engineered plasmids serve as vectors to insert foreign DNA into host cells, enabling mass production of proteins and vaccines. Furthermore, pDNA is used in CRISPR-based gene editing, RNA therapeutics, and DNA vaccines. Due to the rapidly increasing use and application of a wide variety of pDNA, analytical methods to characterize their key attributes are vital. Because of their high molecular weight, accurate and fast mass analyses of pDNA, as a measure of quality control, is rather challenging. Here we explore mass photometry (MP) to analyze pDNAs and find that it completely fails using standard procedures as developed for MP on proteins, with masses underestimated by 30-40%. Even though the landing of pDNA during MP analysis can be improved by using coated glass slides, the large dsDNA particles diffract light beyond the diffraction limit, rendering most landing events unusable. To overcome these issues, we introduce a fast (30 s) and simple protocol to convert dsDNA particles rapidly into ssDNA-like particles just prior to analysis and show that these particles behave nearly perfect for MP. Using this protocol accurate and correct masses of pDNAs can be obtained by MP, with values within 1-3% of the expected mass. Using this protocol, MP can be used to mass analyze pDNA constructs from 1 to 15 MDa, suggesting that this approach may be widely adopted within academia and biopharma for essentially all plasmids.

biochemistry↗

bioRxiv2025

Structure of an oxygen-induced tubular nanocompartment in Pyrococcus furiosus

Reactive oxygen species (ROS) pose a significant threat to biological molecules, prompting organisms to develop systems that buffer oxidative stress and contain iron, which otherwise amplifies ROS production. Understanding oxidative stress responses requires identifying the key proteins involved and their cellular organization. Here, we combined proteomics and cryo-EM to investigate the response of the anaerobic hyperthermophilic archaeon Pyrococcus furiosus to oxygen exposure. Proteome analysis revealed a significant upregulation of the oxidoreductase Rubrerythrin (Rbr) under oxidative stress. Cryo-electron tomograms showed the formation of prominent oxidative stress-induced tubules (OSITs). Single-particle cryo-EM and mass spectrometry of enriched OSITs identified them as stacked rings of Rbr homotetramers. The 3.3 [A] structure demonstrates that rubredoxin-like domains mediate homotetramer assembly, suggesting that their oxidation drives OSIT formation. Within OSITs, we discovered virus-like particles formed by a ferritin-like/encapsulin fusion protein with iron hydroxide cores, uncovering a sophisticated organelle that protects P. furiosus from ROS through advanced compartmentalization.

molecular biology↗

bioRxiv2025

A universal spectrum annotator for complex peptidoforms in mass spectrometry-based proteomics

Accurate and comprehensive peptide spectrum annotation is a crucial step to interpret mass spectrometry-based proteomics data. While peak assignment in peptide fragmentation spectra is central to a broad range of proteomics applications, current tools tend to be specialized to a specific task. Here we present a more comprehensive tool, the Annotator, which unifies spectrum annotation for bottom-up, middle-down, top-down, cross-linked, and glycopeptide fragmentation mass spectra, from all fragmentation methods, including all ion types: a/b/c, x/y/z, d/v/w, and immonium ions. The Annotator integrates all known post-translational modifications from common databases and additionally allows for the definition of custom fragmentation models and modifications. Modifications allow for diagnostic fragment ions, site specific neutral losses, and multiple breakage sites for cross-linkers. The underlying library used for the theoretical fragmentation and matching is based on the unified peptidoform notation ProForma 2.0 and made available as a Rust library (rustyms) with Python bindings. This enables spectrum annotation of diverse and complex peptidoforms across the broad range of mass spectrometry-based proteomics applications.

bioinformatics↗

bioRxiv2024

Sensitivity to Vγ9Vδ2TCR T cells is imprinted after single mutations during early oncogenesis

V{gamma}9V{delta}2T cells have the unique ability to recognize a broad range of malignant transformed cells. The tumor targeting event involving BTN2A1 and BTN3A1 dimers on the tumor cell surface is critical, leading to full activation of the TCR. Although the molecular mechanisms governing TCR engagement and T cell activation are well-characterized, the role of V{gamma}9V{delta}2 T cells in cancer immune surveillance remains to be fully elucidated, particularly the mechanisms that enable these cells to discriminate between healthy and malignant cells at an early stage of malignant transformation. We employed two independent, genetically engineered step-wise mutagenesis models of human colorectal and breast cancer that mimic the transformation steps leading to tumor formation. We demonstrate that various single oncogenic mutations introduced into healthy organoids or cells, are sufficient to upregulate surface expressed BTN2A1 and enable V{gamma}9V{delta}2 TCR binding to tumor cells. However, full activation of T cells through a V{gamma}9V{delta}2TCR required additional subsequent phosphorylation of juxtamembrane (JTM) amino acids of BTN3A1, leading to the activating heterodimerization of BTN2A1 and 3A1. Using a protein interactome mapping pipeline, we identified PHLDB2, SYNJ2 and CARMIL1 as key players in controlling these delicate dual surface dynamics of BTN2A1 and 3A1 during early transformation. This mode of action allowed V{gamma}9V{delta}2TCR T cells to control tumors in vitro and in vivo, emphasizing the crucial role of these molecules from early mutagenesis, to advanced cancer stages, and highlighting the therapeutic potential of a V{gamma}9V{delta}2TCR.

cancer biology↗