The Legionella SidE effectors ubiquitinate host proteins independently of the canonical E1-E2 cascade. Here we engineer the SidE ligases to develop a modular proximity ligation approach for the identification of targets of small molecules and proteins, which we call SidBait. We validate the method with known small molecule-protein interactions and use it to identify CaMKII as an off-target interactor of the breast cancer drug ribociclib. Structural analysis and activity assays confirm that ribociclib binds the CaMKII active site and inhibits its activity. We further customize SidBait to identify protein-protein interactions and discover the F-actin capping protein (CapZ) as a target of the Legionella effector RavB during infection. Structural and biochemical studies indicate that RavB allosterically binds CapZ and decaps actin, thus functionally mimicking eukaryotic CapZ interacting proteins. Collectively, our results establish SidBait as a reliable tool for identifying targets of small molecules and proteins.

Across all domains of life, organisms exploit NAD+ metabolism as a central line of defense against invading pathogens. Here, we show that domain of unknown function 4062 (DUF4062) is a widespread family of TIR-like NADases that hydrolyze NAD+ to ADP-ribose and nicotinamide. In bacteria, DUF4062 homologs form a previously unrecognized antiphage defense system, which we name Swarożyc, that assembles with the phage portal into a supramolecular NADase complex to induce abortive infection. In eukaryotes, DUF4062 is found in TEP1, which we demonstrate functions as an active NADase within the RNA vault, an enigmatic organelle-like structure. Single-particle cryo-electron microscopy reveals ADP-ribose bound within the shoulder of both reconstituted and human brain vaults, while cryo-electron tomography positions TEP1 along the central axis at the shoulder. Thus, TEP1, like bacterial Swarożyc, functions by depleting NAD+, providing new insight into the long-standing mystery of vault function.

The utilization of PD1 and CTLA4 inhibitors has revolutionized the treatment of malignant melanoma (MM). However, resistance to targeted and immune-checkpoint-based therapies still poses a significant problem. Here, we mine large-scale MM proteogenomic data to identify druggable targets and forecast treatment efficacy and resistance. Leveraging protein profiles from established MM subtypes and molecular structures of 82 cancer treatment drugs, we identified nine candidate hub proteins, mTOR, FYN, PIK3CB, EGFR, MAPK3, MAP4K1, MAP2K1, SRC, and AKT1, across five distinct MM subtypes. These proteins are potential drug targets applicable to one or multiple MM subtypes. Additionally, by integrating proteogenomic profiles obtained from MM subtypes with MM cell line dependency and drug sensitivity data, we identified a total of 162 potentially targetable genes. Lastly, we identified 20 compounds exhibiting potential drug impact in at least one melanoma subtype. Employing these unbiased approaches, we have uncovered compounds targeting ferroptosis demonstrating a striking 30× fold difference in sensitivity among different subtypes. Our results suggest innovative and novel therapeutic strategies by stratifying melanoma samples through proteomic profiling, offering a spectrum of novel therapeutic interventions and prospects for combination therapy.

Protein AMPylation, the covalent addition of adenosine monophosphate (AMP) to protein substrates, has been known as a post translational modification for over 50 years. Research in this field is largely underdeveloped due to the lack of tools that enable the systematic identification of AMPylated substrates. Here, we address this gap by developing an enrichment technique to isolate and study AMPylated proteins using a nucleotide-binding protein, hinT. Cryo-EM reconstruction of an AMPylated protein bound to hinT provides a structural basis for AMP selectivity. Using structure guided mutagenesis, we optimize enrichment to identify novel substrates of the evolutionarily conserved AMPylase, Selenoprotein O. We show that mammalian Selenoprotein O regulates metabolic flux through AMPylation of key mitochondrial proteins including glutamate dehydrogenase and pyruvate dehydrogenase. Our findings highlight the broader significance of AMPylation, an emerging post translational modification with critical roles in signal transduction and disease pathology. Furthermore, we establish a powerful enrichment platform for the discovery of novel AMPylated proteins to study the mechanisms and significance of protein AMPylation in cellular function.

Melanoma remains the most aggressive form of skin cancer, characterized by high metastatic potential, genetic heterogeneity, and resistance to conventional therapies. The Melanoma MEGA-Study is a multi-center initiative designed to address these clinical challenges by integrating advanced proteogenomic profiling, clinical metadata, with AI-driven digital pathology and machine learning analytics, aiming to enhance personalized treatment strategies and improve patient outcomes. Between 2013 and 2022, a cohort of 1653 melanoma patients each contributed a primary tumor sample, with 361 providing 819 metastatic tumor samples. Clinical data collection for this cohort continued until May 2023. Comprehensive analyses using high-resolution mass spectrometry, optimized workflows for formalin-fixed paraffin-embedded tissues, and advanced digital pathology platforms enabled precise mapping of the tumor microenvironment, identification of metabolic reprogramming, and characterization of immune evasion signatures. The European Cancer Moonshot Lund Center's MEGA-Study, under the academic umbrella of Lund and Szeged universities, marks a significant advancement in its collaborative efforts with the National Institutes of Health (NIH) under the Cancer Moonshot partnership. This initiative exemplifies the center's dedication to pioneering cancer research and underscores the strength of its international collaborations. SIGNIFICANCE: The significance of this study lies in its pioneering integration of high-resolution proteomics, AI-driven digital pathology, and comprehensive clinical annotation to unravel the complex molecular landscape of melanoma. By leveraging a robust, population-based cohort of 1653 patients, including extensive analyses of both primary and metastatic tumor specimens, our approach provides unprecedented insights into the proteogenomic alterations that underpin tumor progression, immune evasion, and therapeutic resistance. The preliminary application of advanced mass spectrometry techniques to formalin-fixed paraffin-embedded tissues, combined with state-of-the-art digital pathology and machine learning, has enabled the identification of novel protein biomarkers and metabolic signatures that hold promise for refining patient stratification and informing personalized treatment strategies. This integrative framework not only deepens our understanding of melanoma biology but also establishes a scalable model for precision oncology that can be extended to other complex malignancies. Ultimately, our findings have the potential to transform clinical practice by facilitating earlier risk stratification, improving prognostication, and guiding the development of targeted therapeutic interventions for this highly aggressive cancer.

ADP-ribosyltransferases (ARTs) are a superfamily of enzymes implicated in various cellular processes, including pathogenic mechanisms. The Legionella genus, known for causing Legionnaires’ disease, possesses diverse ART-like effectors. This study explores the proteomes of 41 Legionella species to bioinformatically identify and characterise novel ART-like families, providing insights into their potential roles in pathogenesis and host interactions. Our analysis identified 63 proteins with convincing similarity to ARTs, organised into 39 ART-like families, including 26 novel families. Key findings include: ● DUF2971 family: exhibits sequence similarity to DarT toxins and other DNA-acting ARTs. ● DUF4291 family: the largest newly identified family shows structural and sequence similarity to the diphtheria toxin, suggesting the ability to modify proteins. Most members of the novel ART families are predicted effectors. Although experimental validation of the predicted ART effector functions is necessary, the novel ART-like families identified present promising targets for understanding Legionella pathogenicity and developing therapeutic strategies. We published a complete catalogue of our results in the astARTe database: http://bioinfo.sggw.edu.pl/astarte/ . Detailed bioinformatic analyses of the proteomes of pathogenic bacteria reveal novel enzyme families likely involved in interactions with the host.

Using several melanoma proteomics data sets we created a single analysis platform that enables the discovery, knowledge build, and validation of diagnostic, predictive, and prognostic biomarkers at the protein level. Quantitative mass-spectrometry-based proteomic data was obtained from five independent cohorts, including 489 tissue samples from 394 patients with accompanying clinical metadata. We established an interactive R-based web platform that enables the comparison of protein levels across diverse cohorts, and supports correlation analysis between proteins and clinical metadata including survival outcomes. By comparing differential protein levels between metastatic, primary tumor, and nonmalignant samples in two of the cohorts, we identified 274 proteins showing significant differences among the sample types. Further analysis of these 274 proteins in lymph node metastatic samples from a third cohort revealed that 45 proteins exhibited a significant effect on patient survival. The three most significant proteins were HP (HR = 4.67, p = 2.8e-06), LGALS7 (HR = 3.83, p = 2.9e-05), and UBQLN1 (HR = 3.2, p = 4.8e-05). The user-friendly interactive web platform, accessible at https://www.tnmplot.com/melanoma, provides an interactive interface for the analysis of proteomic and clinical data. The MEL-PLOT platform, through its interactive capabilities, streamlines the creation of a comprehensive knowledge base, empowering hypothesis formulation and diligent monitoring of the most recent advancements in the domains of biomedical research and drug development.

Protein AMPylation is a highly conserved posttranslational modification in which adenosine monophosphate (AMP) is covalently attached to protein substrates. Our studies revealed that the mitochondrial AMPylase, Selenoprotein O (SelO), regulates cellular metabolism and oxidative stress response through AMPylation of key metabolic enzymes. Remarkably, SelO-mediated AMPylation is conserved in bacteria and humans, yet the enzyme that removes the AMP from modified proteins remains unknown. We show that the ribonuclease, RNase Z, is both necessary and sufficient to catalyze deAMPylation of AMPylated substrates. These results establish RNase Z as a moonlighting enzyme with previously unrecognized functional roles beyond tRNA processing, expanding our understanding of its biological significance. Furthermore, identification of an evolutionarily conserved deAMPylase highlights the importance of reversible AMPylation as a biological regulatory mechanism, akin to well-studied post translational modifications such as protein phosphorylation.

BACKGROUND:Melanoma, the deadliest form of skin cancer, exhibits resistance to conventional therapies, particularly in advanced and metastatic stages. Mitochondrial pathways, including oxidative phosphorylation and mitochondrial translation, have emerged as critical drivers of melanoma progression and therapy resistance. This study investigates the mitochondrial proteome in melanoma to uncover novel therapeutic vulnerabilities. METHODS:Quantitative proteomics was performed on 151 melanoma-related samples from a prospective cohort and postmortem tissues. Differential expression analysis identified mitochondrial proteins linked to disease aggression and treatment resistance. Functional enrichment analyses and in vitro validation using mitochondrial inhibitors were conducted to evaluate therapeutic potential. RESULTS:Mitochondrial translation and oxidative phosphorylation (OXPHOS) were significantly upregulated in aggressive melanomas, particularly in BRAF-mutant and metastatic tumors. Inhibition of mitochondrial pathways using antibiotics (doxycycline, tigecycline, and azithromycin) and OXPHOS inhibitors (VLX600, IACS-010759, and BAY 87-2243) demonstrated dose-dependent antiproliferative effects in melanoma cell lines, sparing noncancerous melanocytes. These treatments disrupted mitochondrial function, suppressed key metabolic pathways, and induced apoptosis, highlighting the clinical relevance of targeting these pathways. CONCLUSIONS:This study reveals mitochondrial pathways as critical drivers of melanoma progression and resistance, providing a rationale for targeting mitochondrial translation and OXPHOS in advanced melanoma. Combining mitochondrial inhibitors with existing therapies could overcome treatment resistance and improve patient outcomes.

BACKGROUND:Metastatic melanoma is a highly aggressive disease with poor survival rates despite recent therapeutic advancements with immunotherapy. The proteomic landscape of advanced melanoma remains poorly understood, especially regarding proteomic heterogeneity across metastases within patients. METHODS:We collected 83 melanoma metastases from 19 different metastatic sites in 24 patients with advanced metastatic melanoma almost exclusively from the pre-immunotherapy era, using semi-rapid autopsies. The metastases were subjected to histopathological evaluation, RNA-sequencing and mass spectrometry-based proteomics for protein quantitation and non-reference peptide (NRP) sequence detection using a proteogenomic data integration approach. RESULTS:NRPs associated with mutations frequently occurred in proteins related to focal adhesion, vesicle-mediated transport, MAPK signalling and immune response pathways across the cohort. Intrapatient heterogeneity was negligible when considering morphology and driver gene mutation status but was substantial at the proteogenomic level. This heterogeneity was not driven by metastasis location, albeit liver metastases exhibited distinct proteogenomic patterns, including upregulation of metabolic pathways. Cluster analysis outlined four proteomic clusters (C1-4) of the metastases, characterised by the upregulation of cell cycle and RNA-splicing (C1), mitochondrial processes (C3), extracellular matrix (ECM) and immune pathways (C2) and ECM and vesicle-mediated transport pathways (C4). Around two-thirds of patients had metastases that had strongly distinct phenotypes. Patients in our cohort whose metastases were primarily assigned to clusters C1 and C3 exhibited shorter overall survival than patients whose metastases were categorised mainly into the C2 and C4 clusters. CONCLUSION:Our unique multi-metastasis cohort captured the proteogenomic heterogeneity of immunotherapy-naïve melanoma distant metastases, establishing a foundation for future studies aimed at identifying novel therapeutic targets to complement current immunotherapies. KEY POINTS:Comprehensive proteogenomic profiling of post-mortem melanoma metastases, collected primarily before the immunotherapy era. Description of 1177 protein sequence variants predicted by RNA-Seq and validated via mass spectrometry-based proteomics. Empirical evidence of prominent intrapatient heterogeneity, driven by heterogeneous protein expression related to cell cycle- and mitochondrial processes, immune system and extracellular matrix organization.

### Competing Interest Statement The authors have declared no competing interest. National Science Center, https://ror.org/03ha2q922, 2018/31/D/NZ3/03296

In Drosophila ovaries, germ cells differentiate through several stages of cyst development before entering meiosis. This early differentiation program depends on both the stepwise deployment of specific regulatory mechanisms and on maintenance of germline sexual identity. The study of female sterile mutations that result in formation of germ cell tumors has been invaluable in identifying the mechanisms that control these developmental events. Here, we characterize the germ cell-enriched gene bourbon (bbn), null mutants of which cause the formation of a mixture of agametic ovarioles and cystic germ cell tumors. We performed proteomic analysis and found Bbn forms a complex with Ovarian tumor (Otu), a protein previously linked with regulation of the sex determination factor Sex lethal (Sxl), and the Drosophila ortholog of c-Myc binding protein (Mycbp). Loss of Mycbp also results in the formation of cystic germ cell tumors. Bbn promotes the stability of Otu and fosters interactions between Otu and Mycbp. Germ cells from bbn and Mycbp mutants display a loss of Sxl expression specifically in the germline. Transgenic rescue experiments show the bbn sterile phenotype is independent from Sxl splicing defects. Further evidence suggests Otu physically interacts with and promotes Sxl protein stability. This function does not depend on Otu's deubiquitinase activity. Last, we find the human orthologs of Otu and Mycbp, OTUD4, and MYCBP, also physically interact, suggesting conservation of function. Together these data provide insights into how a conserved complex promotes the germline expression of Sxl protein and the differentiation of Drosophila germ cells.

Ether lipids play critical roles in membrane dynamics, antioxidant defense, and signaling. They comprise ∼20% of mammalian phospholipids, and disruptions in their metabolism cause severe genetic disorders and are associated with neurodegenerative and metabolic diseases. Ether lipids are synthesized de novo from glycolytic intermediates or salvaged from the diet. While the products of these pathways are known, several key enzymes remain unidentified, including the 1-O-alkylglycerol kinase and the 1-O-alkyl-2-acetyl- sn -glycero-3-phosphate phosphatase. Here, we show that acyl-CoA dehydrogenase member 10 (ACAD10) catalyzes the phosphorylation of 1-O-alkylglycerols and the dephosphorylation of 1-O-alkyl-2-acetyl- sn -glycero-3-phosphate. Worms and mice lacking ACAD10 have reduced ether lipid levels and cannot salvage dietary alkylglycerols. Furthermore, individuals from the Akimel O’odham (Pima) tribe carrying ACAD10 polymorphisms also show decreased plasma ether lipid levels. Collectively, our findings resolve two long-standing gaps in ether lipid biochemistry and reveal a mechanistic link between ether lipid metabolism and a population-associated risk factor for type 2 diabetes. ### Competing Interest Statement The authors have declared no competing interest. National Institutes of Health, https://ror.org/01cwqze88, DP2GM137419, R01DK137976, R35GM158265, R01DK133479 Welch Foundation, I-1911 Howard Hughes Medical Institute, https://ror.org/006w34k90 Glenn Foundation for Medical Research, https://ror.org/02ebg5q27, A22068 Hatch Grant

This white paper presents a comprehensive biobanking framework developed at the European Cancer Moonshot Lund Center that merges rigorous sample handling, advanced automation, and multi-omic analyses to accelerate precision oncology. Tumor and blood-based workflows, supported by automated fractionation systems and standardized protocols, ensure the collection of high-quality biospecimens suitable for proteomic, genomic, and metabolic studies. A robust informatics infrastructure, integrating LIMS, barcoding, and REDCap, supports end-to-end traceability and realtime data synchronization, thereby enriching each sample with critical clinical metadata. Proteogenomic integration lies at the core of this initiative, uncovering tumor- and blood-based molecular profiles that inform cancer heterogeneity, metastasis, and therapeutic resistance. Machine learning and AI-driven models further enhance these datasets by stratifying patient populations, predicting therapeutic responses, and expediting the discovery of actionable targets and companion biomarkers. This synergy between technology, automation, and high-dimensional data analytics enables individualized treatment strategies in melanoma, lung, and other cancer types. Aligned with international programs such as the Cancer Moonshot and the ICPC, the Lund Center's approach fosters open collaboration and data sharing on a global scale. This scalable, patient-centric biobanking paradigm provides an adaptable model for institutions aiming to unify clinical, molecular, and computational resources for transformative cancer research.

The kinase-like nidovirus RdRp-associated nucleotidyl transferase (NiRAN) domain of nsp12 in SARS-CoV-2 catalyzes the formation of the 5' RNA cap structure. This activity is required for viral replication, offering a new target for the development of antivirals. Here, we develop a high-throughput assay to screen for small molecule inhibitors targeting the SARS-CoV-2 NiRAN domain. We identified NiRAN covalent inhibitor 2 (NCI-2), a compound with a reactive chloromethyl group that covalently binds to an active site cysteine (Cys53) in the NiRAN domain, inhibiting its activity. NCI-2 can enter cells, bind to, and inactivate ectopically expressed nsp12. A cryo-EM reconstruction of the SARS-CoV-2 replication-transcription complex bound to NCI-2 offers a detailed structural blueprint for rational drug design. Although NCI-2 showed limited potency against SARS-CoV-2 replication in cells, our work lays the groundwork for developing more potent and selective inhibitors targeting the NiRAN domain. This approach presents a promising therapeutic strategy for effectively combating COVID-19 and potentially mitigating future coronavirus outbreaks.

Background: Melanoma is a highly heterogeneous disease, and a deeper molecular classification is essential for improving patient stratification and treatment approaches. Here, we describe the histopathology-driven proteogenomic landscape of 142 treatment-naïve metastatic melanoma samples to uncover molecular subtypes and clinically relevant biomarkers. Methods: We performed an integrative proteogenomic analysis to identify proteomic subtypes, assess the impact of BRAF V600 mutations, and study the molecular profiles and cellular composition of the tumor microenvironment. Clinical and histopathological data were used to support findings related to tissue morphology, disease progression, and patient outcomes. Results: Our analysis revealed five distinct proteomic subtypes that integrate immune and stromal microenvironment components and correlate with clinical and histopathological parameters. We demonstrated that BRAF V600-mutated melanomas exhibit biological heterogeneity, where an oncogene-induced senescence-like phenotype is associated with improved survival. This led to a proposed mortality risk-based stratification that may contribute to more personalized treatment strategies. Furthermore, tumor microenvironment composition strongly correlated with disease progression and patient outcomes, highlighting a histopathological connective tissue-to-tumor ratio assessment as a potential decision-making tool. We identified a melanoma-associated SAAV signature linked to extracellular matrix remodeling and SAAV-derived neoantigens as potential targets for anti-tumor immune responses. Conclusions: This study provides a comprehensive stratification of metastatic melanoma, integrating proteogenomic insights with histopathological features. The findings may aid in the development of tailored diagnostic and therapeutic strategies, improving patient management and outcomes.