Biology subjects

Jooss, K.

Publications and source records attributed to Jooss, K..

7 recordsLinked to original sources

bioRxiv2025

Direct Readout of Multivalent Chromatin Reader-Nucleosome Interactions by Nucleosome Mass Spectrometry

Histone post-translational modifications (PTMs) often serve as distinct recognition sites for the recruitment of chromatin-associated proteins (CAPs) for epigenome regulation. While CAP-PTM interactions have been extensively studied using histone peptides, this cannot consider the regulatory potential of multi-site binding on intact nucleosomes. To overcome this limitation, we applied Nucleosome Mass Spectrometry (Nuc-MS), a native Top-Down MS approach that enables controlled disassembly of intact CAP:nucleosome (CAP:nuc) complexes to provide a direct readout of the contained histone proteoforms. As proof of principle, we show the BPTF PHD-BD native tandem reader requires coincident H3K4me3K9acK14acK18ac for effective nucleosome engagement. We extend our approach to explore how the BRD4 (native BD1-BD2), DNMT3A-MPP8 (chimeric PWWP-CD), and PtSHL (native BAH-BD) tandem readers interact with endogenous nucleosomes. Each reveals distinct enrichment profiles: BRD4 favoring di- and tri-acetylated histone H4 proteoforms, whereas DNMT3A-MPP8 and PtSHL preferentially interact with hypermethylated H3 proteoforms. Of note the latter enriches combinatorial {H3K4me3K27me3} on the same histone tail in HeLa chromatin, and thus expands the potential biology of this widely studied bivalent signature. By directly characterizing CAP:nuc complex composition with combinatorial PTM information in a single readout, Nuc-MS serves as a new approach to discover the modifications driving binding, and therefore primary candidates to explore for structural biology and genomic studies. O_FIG O_LINKSMALLFIG WIDTH=199 HEIGHT=200 SRC="FIGDIR/small/651740v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@8815e9org.highwire.dtl.DTLVardef@5685b5org.highwire.dtl.DTLVardef@643881org.highwire.dtl.DTLVardef@1b9bc20_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOFor TOC only.C_FLOATNO Synopsis. Nuc-MS provides the ability to control the disassembly of chromatin-associated protein-nucleosome complexes (CAP-nuc) and delineate the histone proteoforms driving tandem reader domain binding. C_FIG

biochemistry↗

bioRxiv2024

A novel HLA Class II presentation prediction algorithm deciphers immunogenic CD4 epitopes specific to KRAS G12C

Accurate prediction of peptide presentation by HLA molecules is important for generation of effective individualized cancer vaccines and immunotherapies. While presentation prediction algorithms for HLA class I have been successfully applied in the context of such therapies, improved prediction algorithms for class II are needed. EDGE-II is a novel algorithm based on a protein large language model that has a learned allele deconvolution network trained on existing and new immunopeptidomics data. It delivers state-of-the-art performance on prediction of peptide presentation by HLA class II and immunogenicity elicited by CD4+ T-cell epitopes. In a patient with a KRAS G12C positive tumor treated with a KRAS G12C targeting immunotherapy, EDGE-II identified KRAS G12C class II neoantigens that elicited clonally expanded CD4+ T cells with cytotoxic transcriptional profiles post-vaccination. EDGE-II could play an important role in the development of effective cancer immunotherapies by elucidating an enriched understanding of the immunopeptidome.

bioinformatics↗

bioRxiv2024

Comprehensive Longitudinal ctDNA Monitoring in Metastatic Cancer Patients Treated with an Individualized Neoantigen-directed Vaccine

PurposeCirculating-tumor DNA (ctDNA) is an emerging, minimally invasive diagnostic and prognostic biomarker for patients receiving a variety of cancer therapies. Comprehensive and robust longitudinal monitoring of ctDNA can provide an understanding of tumor burden, heterogeneity, and response or resistance to treatment. Experimental DesignctDNA of 28 metastatic cancer patients receiving an individualized neoantigen-directed immunotherapy was monitored longitudinally, up to two years, using a unique hybrid next generation sequencing assay targeting tumor-informed and tumor-naive variants. Patient-specific panels were designed targeting an average of 144 variants per patient. A tumor-naive universal panel was also designed for inclusion with patient-specific panels to monitor recurrently mutated tumor hotspots (e.g., KRAS and TP53) and genes implicated in immunotherapy resistance (B2M, TAP1/2). ResultsAnalytical characterization of the assay established linearity with a mean variant allele frequency (VAF) [≥]0.049%, and a variant-level limit of detection (LOD95) of 0.12%. Tumor-informed variants were detected in 26/28 patients, and de novo variants were observed in 25/28 patients. HLA LOH was also observed. Longitudinal ctDNA data provided key insights into patients responses to vaccine treatment. ConclusionsThe hybrid design of the ctDNA monitoring assay provides the sensitivity and specificity required for evaluating patient samples undergoing individualized therapy. It provides an improved capability to understand patient response to experimental therapies and further supports the utility of ctDNA as a cancer biomarker.

genomics↗

bioRxiv2021

A self-amplifying mRNA COVID-19 vaccine drives potent and broad immune responses at low doses that protects non-human primates against SARS-CoV-2

The coronavirus disease 2019 (COVID-19) pandemic continues to spread globally, highlighting the urgent need for safe and effective vaccines that could be rapidly mobilized to immunize large populations. We report the preclinical development of a self-amplifying mRNA (SAM) vaccine encoding a prefusion stabilized severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike glycoprotein and demonstrate potent cellular and humoral immune responses at low doses in mice and rhesus macaques. The homologous prime-boost vaccination regimen of SAM at 3, 10 and 30 g induced potent neutralizing antibody titers in rhesus macaques following two SAM vaccinations at all dose levels, with the 10 g dose generating geometric mean titers (GMT) 48-fold greater than the GMT of a panel of SARS-CoV-2 convalescent human sera. Spike-specific T cell responses were observed at all dose levels. SAM vaccination provided protective efficacy against SARS-CoV-2 challenge as both a homologous prime-boost and as a single boost following ChAd prime, demonstrating reduction of viral replication in both the upper and lower airways. Protection was most effective with a SAM prime-boost vaccination regimen at 10 and 30 g and with a ChAd/SAM heterologous prime-boost regimen. The SAM vaccine is currently being evaluated in clinical trials as both a homologous prime-boost regimen at low doses and as a boost following heterologous prime.

immunology↗

bioRxiv2020

Separation and Characterization of Endogenous Nucleosomes by Native Capillary Zone Electrophoresis - Top-Down Mass Spectrometry (nCZE-TDMS)

We report a novel platform (native capillary zone electrophoresis - top-down mass spectrometry; nCZE-TDMS) for the separation and characterization of whole nucleosomes, their histone subunits, and PTMs. As the repeating unit of chromatin, mononucleosomes (Nucs) are a ~200 kDa complex of DNA and histone proteins involved in the regulation of key cellular processes central to human health and disease. Unraveling the covalent modification landscape of histones and their defined stoichiometries within Nucs helps to explain epigenetic regulatory mechanisms. In nCZE-TDMS, online Nuc separation is followed by a three-tier tandem MS approach that measures the intact mass of Nucs, ejects and detects the constituent histones, and fragments to sequence the histone. The new platform was optimized with synthetic Nucs to reduce both sample requirements and cost significantly compared to direct infusion. Limits of detection were in the low attomole range, with linearity over ~three orders of magnitude. The nCZE-TDMS platform was applied to endogenous Nucs from two cell lines distinguished by overexpression or knockout of histone methyltransferase NSD2/MMSET, where analysis of constituent histones revealed changes in histone abundances over the course of the CZE separation. We are confident the nCZE-TDMS platform will help advance nucleosome-level research in the fields of chromatin and epigenetics.

biochemistry↗

bioRxiv2020

Standard Procedures for Native CZE-MS of Proteins and Protein Complexes up to 800 kDa

Native mass spectrometry (nMS) is a rapidly growing method for the characterization of large proteins and protein complexes, preserving "native" non-covalent inter- and intramolecular interactions. Direct infusion of purified analytes into a mass spectrometer represents the standard approach for conducting nMS experiments. Alternatively, CZE can be performed under native conditions, providing high separation performance while consuming trace amounts of sample material. Here, we provide standard operating procedures for acquiring high quality data using CZE in native mode coupled online to various Orbitrap mass spectrometers via a commercial sheathless interface, covering a wide range of analytes from 30 - 800 kDa. Using a standard protein mix, the influence of various CZE method parameters were evaluated, such as BGE/conductive liquid composition and separation voltage. Additionally, a universal approach for the optimization of fragmentation settings in the context of protein subunit and metalloenzyme characterization is discussed in detail for model analytes. A short section is dedicated to troubleshooting of the nCZE-MS setup. This study is aimed to help normalize nCZE-MS practices to enhance the CE community and provide a resource for production of reproducible and high-quality data.

biochemistry↗

bioRxiv2020

Decoding the Protein Composition of Whole Nucleosomes with Nuc-MS

Nuc-MS characterizes histone modifications and variants directly from intact endogenous nucleosomes. Preserving whole nucleosome particles enables precise interrogation of their protein content, as for H3.3-containing nucleosomes which had 6-fold co-enrichment of variant H2A.Z over bulk chromatin. Nuc-MS, validated by ChIP-seq, showed co-occurrence of oncogenic H3.3K27M with euchromatic marks (e.g., H4K16ac and >15-fold enrichment of H3K79me2). By capturing the entire epigenetic landscape, Nuc-MS provides a new, quantitative readout of nucleosome-level biology.

biochemistry↗