Biology subjects

Machado, P.

Publications and source records attributed to Machado, P..

At least 19 recordsLinked to original sources

bioRxiv2026

LC3C-ATG4D regulatory axis supports coronavirus replication organelle formation independently of canonical autophagy

Coronaviruses hijack host membranes to assemble ER-derived double-membrane vesicles (DMVs) that shield viral RNA replication from the cell intrinsic surveillance. Although DMVs morphologically resemble autophagosomes, whether and how autophagy factors actively support their biogenesis has remained elusive. Here, we identify a non-canonical requirement for the autophagy protein LC3C in {beta}-coronavirus replication. Loss of LC3s impaired viral RNA replication, whereas genetic ablation of ATG7 did not, indicating that canonical ATG7-dependent lipidation is dispensable in this context. Reconstitution experiments showed that only LC3C substantially restored replication in LC3-deficient cells and that LC3C phospho-mutants, differing in accessibility to ATG4-mediated processing, displayed distinct proviral activities. Additionally, ATG4D, the main protease responsible for maintaining the LC3 non-lipidated pool, is selectively required for viral replication. Both ATG4D and LC3s depletion triggers formation of aberrant DMV-like structures and potently suppresses SARS-CoV-2 replication. Ultrastructural analysis of nsp3-nsp4-induced membranes showed that depletion of LC3s or ATG4 proteases altered DMV abundance and morphology, supporting a role for the LC3C-ATG4D axis in replication organelle biogenesis. These data establish that {beta}-coronaviruses repurpose ATG4D-driven LC3C de-lipidation for non-canonical LC3 recruitment to replication organelles, identifying the lipidation state of LC3 as a molecular determinant of replication organelle biogenesis and efficient viral replication. HighlightsThe manuscript shows that {beta}-coronavirus replication depends on LC3 proteins and particularly on LC3C in reconstitution experiments, that this dependency is independent of ATG7-mediated lipidation, and that ATG4D promotes efficient replication and replication organelle morphology. Together, the data support a model in which a non-canonical LC3C-ATG4D pathway contributes to DMV biogenesis and viral RNA replication.

cell biology↗

bioRxiv2025

From 2D Monolayer to 3D Spheroid: Matrigel's Spatial and Chemical Cues Remodel the Calu-3 Proteome

The limited physiological relevance of conventional 2D cell cultures hampers translational research. While 3D cultures offer a superior alternative, their reliance on undefined scaffolds like Matrigel makes it difficult to distinguish cellular responses to physical architecture from those to biochemical cues. This study provides a high-resolution, label-free quantitative comparison of the Calu-3 lung adenocarcinoma proteome in 2D monolayers versus 3D Matrigel-embedded spheroids. To further dissect the specific contributions of 3D architecture versus biochemical cues from the matrix, we included an intermediate condition where a 2D monolayer was cultured in contact with Matrigel droplets (2M). After a stringent data analysis pipeline that controlled for matrix contamination, we quantified over 3,900 human proteins and revealed that 3D culture architecture is the dominant driver of proteomic remodeling. We identified 72 differentially enriched and 48 conditionally quantified proteins distinguishing the 3D spheroids from monolayers, functionally characterized by a down-regulation of cell-surface and cholesterol biosynthesis proteins and an up-regulation of proteins associated with iron clusters. While direct comparison between the two bidimensional cultures yielded no significant differences, a dedicated paired statistical analysis demonstrated that biochemical cues from Matrigel alone prompted a subtle but significant proteome-wide shift, moving the cells closer to the 3D phenotype. This study delivers a detailed blueprint of the profound proteomic reprogramming induced by 3D culture and, by isolating the matrixs biochemical influence, provides a critical resource for rational model selection and the design of defined synthetic matrices.

cell biology↗

bioRxiv2025

TDP-43 pathology induces CD8+ T cell activation through cryptic epitope recognition

Aggregation and nuclear depletion of the RNA binding protein TDP-43 are the crucial pathological features of amyotrophic lateral sclerosis (ALS) and inclusion body myositis (IBM), two degenerative diseases of the CNS and muscle. The loss of TDP-43 nuclear function results in the aberrant inclusion of cryptic exons in mRNA transcripts, leading to the expression of de novo proteins. Clonally expanded and highly differentiated CD8+ T cells have been observed in individuals with TDP-43 proteinopathies and therapeutics modulating the T cell response have recently been found to extend survival. However, the target antigens mediating T cell activation have remained elusive. Here, we investigate whether the de novo proteins induced by aberrant cryptic splicing due to TDP-43 nuclear loss can act as neo-antigens. We detect the HDGFL2 cryptic peptide and multiple other TDP-43 cryptic exons in IBM skeletal muscle, where their presence correlates with enrichment of T cells and class I antigen presentation pathways. Furthermore, we identify epitopes deriving from HDGFL2 and IGLON5 cryptic peptides which are recognized by clonally expanded and functionally differentiated populations of CD8+ T cells in ALS and IBM Patients. Finally, we demonstrate that T cells engineered to express the identified TCRs can bind and activate in response to the cryptic peptide derived epitopes (cryptic epitopes) and are able to kill TDP-43 deficient astrocytes. This work identifies for the first time specific T cell antigens in ALS and IBM, directly linking adaptive immune response to TDP-43 pathology.

immunology↗

bioRxiv2024

The Porphyromonas gingivalis lipid A 1-phosphatase LpxE has unique features and requires a functional type IX secretion system for its activity

Porphyromonas gingivalis is a Gram-negative bacterium that plays a central role in the development of periodontal disease. It uses a type IX secretion system (T9SS) to export a range of virulence factors to the bacterial surface where they are attached to A-LPS, one of the two forms of lipopolysaccharide (LPS) produced in P. gingivalis, and then packaged into outer membrane vesicles (OMVs). We previously showed that 1-P dephosphorylation of the lipid A component of LPS is regulated by the T9SS outer membrane protein (OMP) PorV, and this is linked to membrane destabilisation and OMV blebbing/formation. In this study we aimed to extend this and investigate the role of other T9SS OMPs in OMV biogenesis. We examined gingipain activity, gingipain secretion, A-LPS production, OMV morphology, and lipid A structure in P. gingivalis W50 and T9SS OMP mutant strains, and our results support an essential role for these proteins in type IX secretion. In addition, we produced a lipid A 1-phosphatase ({Delta}lpxE) mutant and show that all T9SS OMPs are required for LpxE activity and correct vesicle formation. LpxE has a unique C-terminal extension, and we propose that a cargo protein exported by the T9SS can directly/indirectly interact with this and regulate LpxE activity. This study provides insight into a new mechanism that links type IX cargo sorting with OMV blebbing, which may also be present in other Bacteroidota that colonise the gut and oral cavity.

microbiology↗

bioRxiv2024

The isoniazid analog IQG-607 is not a direct substrate for the Mycobacterium tuberculosis catalase-peroxidase KatG

Tuberculosis (TB) is an infectious disease caused mainly by Mycobacterium tuberculosis (Mtb) and is responsible for millions of deaths. New Mtb strains resistant to TB drugs are emerging and spreading. The first-line TB drug, isoniazid (INH), must be activated inside mycobacterial cells by the catalase-peroxidase enzyme KatG to exert its antimicrobial activity, and mutations on the katG gene are a significant cause of INH resistance in clinics. The metal-containing compound IQG-607 is an INH analog developed to inhibit the target of INH, the FASII enzyme enoyl-ACP-reductase (InhA), without requiring KatG. However, we recently showed that inside mycobacterial cells, IQG-607 activity depends on KatG. Hence, this compound might also be activated by KatG to inhibit InhA. We evaluated whether recombinant MtKatG uses IQG-607 as a substrate in oxidation reactions and adduct formation with NAD+. A recombinant MtKatG was produced in E. coli and purified in a 3-step protocol to obtain a homogeneous protein. An HPLC method was optimized to monitor both oxidation and adduct products, and our assay system was validated by performing control reactions using INH as a substrate. We found that the metal-based compound IQG-607 is not a substrate for recombinant MtKatG under all conditions tested.

biochemistry↗

bioRxiv2023

ProtPipe: A Multifunctional Data Analysis Pipeline for Proteomics and Peptidomics

Mass spectrometry (MS) is a technique widely employed for the identification and characterization of proteins, personalized medicine, systems biology and biomedical applications. By combining MS with different proteomics approaches such as immunopurification MS, immunopeptidomics, and total protein proteomics, researchers can gain insights into protein-protein interactions, immune responses, cellular processes, and disease mechanisms. The application of MS-based proteomics in these areas continues to advance our understanding of protein function, cellular signaling, and complex biological systems. Data analysis for mass spectrometry is a critical process that includes identifying and quantifying proteins and peptides and exploring biological functions for these proteins in downstream analysis. To address the complexities associated with MS data analysis, we developed ProtPipe to streamline and automate the processing and analysis of high-throughput proteomics and peptidomics datasets. The pipeline facilitates data quality control, sample filtering, and normalization, ensuring robust and reliable downstream analysis. ProtPipe provides downstream analysis including identifying differential abundance proteins and peptides, pathway enrichment analysis, protein-protein interaction analysis, and MHC1-peptide binding affinity. ProtPipe generates annotated tables and diagnostic visualizations from statistical postprocessing and computation of fold-changes across pairwise conditions, predefined in an experimental design. ProtPipe is well-documented open-source software and is available at https://github.com/NIH-CARD/ProtPipe, accompanied by a web interface.

bioinformatics↗

bioRxiv2023

Large-scale proteogenomics characterization of the Mycobacterium tuberculosis hidden microproteome

Tuberculosis remains a burden to this day, due to the rise of multi and extensively drug-resistant bacterial strains. The genome of Mycobacterium tuberculosis (Mtb) underwent an annotation process that excluded small Open Reading Frames (smORFs), which encode a class of peptides and small proteins collectively known as microproteins. As a result, there is an overlooked part of its proteome that is a rich source of potentially essential, druggable molecular targets. Here, we employed our recently developed proteogenomics pipeline to identify novel microproteins encoded by smORFs in the genome of Mtb usings hundreds of mass spectrometry experiments in a large-scale approach. We found protein evidence for hundreds of novel microproteins and identified smORFs potentially involved in bacterial growth and virulence. Moreover, many smORFs are co-expressed or share operons with a myriad of biologically relevant genes and may play a role in antibiotic response. Together, our data presents a resource of unknown genes that play a role in the success of Mtb as a widespread pathogen.

molecular biology↗

bioRxiv2023

Identification and characterization of new structural scaffolds modulating the activity of Mycobacterium tuberculosis dihydroneopterin aldolase (FolB) in vitro

Antifolates were among the first broad-spectrum compounds used as antimycobacterial agents and can still be of use when no other therapeutic options are available. The discovery of compounds targeting this essential pathway could lead to new therapeutic agents to treat tuberculosis (TB). In particular, the enzyme required for the conversion of 7,8-dihydroneopterin (DHNP) to 6-hydroxymethyl-7,8-dihydropterin (HP) and glycolaldehyde (GA) in the folate pathway (MtbFolB, a dihydroneopterin aldolase - DHNA, EC 4.1.2.25), has received little attention as a potential drug target. Here, we conducted a small-scale diversity screening to identify MtbFolB inhibitors using a microplate-based enzyme inhibition assay. About 6,000 compounds were assembled for the screening and 19 hits were identified, spanning 5 independent clusters. These compounds were tested in dose-response studies and active compounds selected for kinetic inhibition and time-dependent inhibition studies, leading to compounds with IC50 values ranging from 2.6 to 47 {micro}M. A preliminary structure activity analysis was performed, revealing that bi-sulfonamide compounds could be explored for further optimizations. Docking studies highlighted two modes of binding for pyrazol-3-one compounds and, for the sulfonamide series, indicated several interactions with the catalytic Tyrosine-54 (Tyr54D) and Lysine-99 (Lys99A) residues of MtbFolB. The sulfonamide compound 13 represents the first identified compound directed against MtbFolB with an antimycobacterial activity.

biochemistry↗

bioRxiv2023

The Integration of Proteogenomics and Ribosome Profiling Circumvents Key Limitations to Increase the Coverage and Confidence of Novel Microproteins

There has been a dramatic increase in the identification of non-conical translation and a significant expansion of the protein-coding genome and proteome. Among the strategies used to identify novel small ORFs (smORFs), Ribosome profiling (Ribo-Seq) is the gold standard for the annotation of novel coding sequences by reporting on smORF translation. In Ribo-Seq, ribosome-protected footprints (RPFs) that map to multiple sites in the genome are computationally removed since they cannot unambiguously be assigned to a specific genomic location, or to a specific transcript in the case of multiple isoforms. Furthermore, RPFs necessarily result in short (25-34 nucleotides) reads, increasing the chance of ambiguous and multi-mapping alignments, such that smORFs that reside in these regions cannot be identified by Ribo-Seq. Here, we show that the inclusion of proteogenomics to create a Ribosome Profiling and Proteogenomics Pipeline (RP3) bypasses this limitation to identify a group of microprotein-encoding smORFs that are missed by current Ribo-Seq pipelines. Moreover, we show that the microproteins identified by RP3 have different sequence compositions from the ones identified by Ribo-Seq-only pipelines, which can affect proteomics identification. In aggregate, the development of RP3 maximizes the detection and confidence of protein-encoding smORFs and microproteins.

bioinformatics↗

bioRxiv2023

Shotgun proteomic analysis of the caterpillar Lonomia obliqua (Lepitoptera, Saturniidae) hemolymph and effects in rat hippocampal neurons culture

Study of substances with potentially neuroprotective has been one of the research focus on drugs development. Toxic proteins of Lonomia obliqua caterpillars, which have caused several accidents in southern Brazil, were identified in the hemolymph with anti-apoptotic activity. This study aims the evaluation of the protein profile and the hemolymph effect on cell viability of rats primary cultured hippocampal neurons after apoptosis induction. Semi-quantitative shotgun proteomics approach was used to evaluate the protein profile of 3 caterpillars lots of different origin. Were identified a total of 76 proteins, 71 in hemolymph and 40 in fractions. Antiviral protein predominated in crude hemolymph, following by serine proteases, hemolins and protease inhibitors. In fractions were identified hemolins, serine proteases and protease inhibitors. The treatment of rats primary cultured hippocampal neurons with the chromatographic fraction at concentration of 0.05 and 0.10% (v/v) for 24 hours, with subsequently apoptosis induction was able to maintain cell viability significantly higher than positive control. Hemolymph protein composition can show qualitative and quantitative variations intra species when compared different origins animals and consequently exposed to various environmental factors. The results shown on this study may contribute to the identification of proteins with potential use as neuroprotective in degenerative conditions.

biochemistry↗

bioRxiv2022

SARS-CoV-2 immune complex triggers human monocyte necroptosis

We analyzed the ability of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) itself and SARS-CoV-2-IgG immune complexes to trigger human monocyte necroptosis. SARS-CoV-2 was able to induce monocyte necroptosis dependently of MLKL activation. Necroptosis-associated proteins (RIPK1, RIPK3 and MLKL) were involved in SARS-CoV-2 N1 gene expression in monocytes. SARS-CoV-2 immune complexes promoted monocyte necroptosis in a RIPK3- and MLKL-dependent manner, and Syk tyrosine kinase was necessary for SARS-CoV-2 immune complex-induced monocyte necroptosis, indicating the involvement of Fc{gamma} receptors on necroptosis. Finally, we provide evidence that elevated LDH levels as a marker of lytic cell death are associated with COVID-19 pathogenesis.

immunology↗

bioRxiv2022

OM-85 reduces SARS-COV-2 viral RNA expression in nasopharyngeal cells from COVID-19 patients

OM-85 is a bacterial lysate from common respiratory tract pathogens, with an excellent safety profile, widely used to prevent recurrent respiratory tract infections. Several studies have been reporting the antiviral roles of OM-85. Here we demonstrated the effect of ex-vivo OM-85 exposure in nasopharyngeal cells collected from COVID-19 patients. OM-85 decreased the SARS-CoV-2 N1 gene expression and increased RIG-I (DDX58) gene expression in these cells. These data support the antiviral effect of OM-85 against SARS-CoV-2.

microbiology↗

bioRxiv2022

Novel repertoire of tau biosensors to monitor pathological tau transformation and seeding activity in living cells

Aggregates of the tau protein are a well-known hallmark of several neurodegenerative diseases, collectively referred as tauopathies, including frontal temporal dementia and Alzheimers disease (AD). Monitoring the transformation process of tau from physiological monomers into pathological oligomers or aggregates in a high-throughput, quantitative manner and in a cellular context is still a major challenge in the field. Identifying molecules able to interfere with those processes is of high therapeutic interest. Here, we developed a series of inter- and intramolecular tau biosensors based on the highly sensitive Nanoluciferase (Nluc) binary technology (NanoBiT) able to monitor the pathological conformational change and self-interaction of tau in living cells. Our repertoire of tau biosensors reliably report i. molecular proximity of physiological full-length tau at microtubules; ii. changes in tau conformation and self-interaction associated with tau phosphorylation, as well as iii. tau interaction induced by seeds of recombinant tau or from mouse brain lysates of a mouse model of tau pathology. By comparing biosensors comprising different tau forms (i.e. full-length or short fragments, wild-type or the disease-associated tau(P301L) variant) further insights in the tau transformation process are obtained. Proof-of-concept data for the high-throughput suitability and identification of molecules interfering with the pathological tau transformation processes are presented. This novel repertoire of tau biosensors is aimed to boost the disclosure of molecular mechanisms underlying pathological tau transformation in living cells and to discover new drug candidates for tau-related neurodegenerative diseases.

cell biology↗

bioRxiv2021

A high throughput SEC23 functional interaction screen reveals a role for focal adhesion and extracellular matrix signalling in the regulation of COPII subunit SEC23A

Proteins that enter the secretory pathway are transported from their place of synthesis in the Endoplasmic Reticulum to the Golgi complex by COPII coated carriers. The components of the COPII transport machinery have been well characterized, but the network of proteins that regulate these components in response to extracellular cues have remained largely elusive. The discovery of such regulatory proteins is crucial for understanding how cells integrate extracellular and intracellular information to fine-tune membrane traffic in the secretory pathway. A key group of proteins that plays a central role in the regulation of membrane traffic is associated with the cytoskeleton. Using high throughput microscopy of the well-established VSVG transport from the ER to the plasma membrane, we comprehensively screened 378 cytoskeleton-associated proteins for their functional interaction with the COPII components SEC23A and SEC23B using a double knockdown approach. Ranking of the transport effectors identified 20 cytoskeleton-associated proteins as the strongest functional interactors of SEC23, most of them not previously associated with the secretory pathway. Knockdown of a subgroup of these interactors (FERMT2, MACF1, MAPK8IP2, NGEF, PIK3CA, ROCK1), associated with cell adhesion, not only induced changes in focal adhesions and the expression of adhesion-related genes but led to the specific downregulation of SEC23A, a SEC23 paralogue that has been implicated in the secretion of extracellular matrix (ECM) components. Furthermore, SEC23A downregulation could also be recapitulated by plating cells on ECM and was dependent on focal adhesions function. Altogether, our results identify a network of cytoskeleton-associated proteins connecting focal adhesions and ECM-related signalling with the gene expression of the COPII secretory machinery.

cell biology↗

bioRxiv2021

Fluorescence-based 3D targeting of FIB-SEM acquisition of small volumes in large samples

Cells are three dimensional objects. Therefore, 3D electron microscopy is often crucial for correct interpretation of ultrastructural data. Today samples are frequently imaged in 3D at ultrastructural resolution using volume Scanning Electron Microscopy (SEM) methods such as Focused Ion Beam (FIB) SEM and Serial Block face SEM. While these imaging modalities allow for automated data acquisition, precise targeting of (small) volumes of interest within a large sample remains challenging. Here, we provide an easy and reliable approach to target FIB-SEM acquisition of fluorescently labelled cells or subcellular structures with micrometer precision. The strategy relies on fluorescence preservation during sample preparation and targeting based on confocal acquisition of the fluorescence signal in the resin block. Targeted trimming of the block exposes the cell of interest and laser branding of the surface after trimming creates landmarks to precisely position the FIB-SEM acquisition. Using this method, we acquired volumes of specific single cells within large tissues such as a 3D culture of mouse primary mammary gland organoids, tracheal terminal cells in Drosophila melanogaster larvae and ovarian follicular cells in adult Drosophila, discovering ultrastructural details that could not be appreciated before. SummaryRonchi et al. present a workflow to facilitate the precise targeting of three-dimensional (3D) Electron Microscopy acquisitions, guided by fluorescence. This method allows ultrastructural visualization of single cells within a millimeter-range large specimen, based on molecular identity characterized by fluorescence.

cell biology↗

bioRxiv2020

Evaluating aroA gene essentiality and EPSP synthase vulnerability in Mycobacterium smegmatis under different nutritional conditions

The epidemiological importance of bacteria from the genus Mycobacterium is indisputable and the necessity to find new molecules that can inhibit their growth is urgent. The shikimate pathway, required for the synthesis of important metabolites in bacteria, represents a target for inhibitors of Mycobacterium tuberculosis growth. The aroA-encoded 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme catalyzes the sixth step of the shikimate pathway. In this study, we combined gene knockout, gene knockdown and kinetic assays to evaluate aroA gene essentiality and the vulnerability of its protein product, EPSPS synthase from Mycobacterium smegmatis (MsEPSPS), under different nutritional conditions. We demonstrate by an allelic exchange-based gene knockout approach the essentiality of MsEPSPS under rich and poor nutritional conditions. By performing gene complementation experiments with wild-type (WT) and point mutant versions of aroA gene, together with kinetic assays using WT and mutant recombinant proteins, we show that aroA gene essentiality depends on MsEPSPS activity. To evaluate MsEPSPS vulnerability, we performed gene knockdown experiments using the Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) system. The experiments were performed in both rich and defined (poor) media, using three different repression forces for aroA gene. We only observed growth impairment when bacteria were grown in defined medium without supplementation of aromatic amino acids, thereby indicating that MsEPSPS vulnerability depends on the environment conditions. ImportanceWe evaluated both gene essentiality and target vulnerability of the enzyme that catalyzes the sixth step of the shikimate pathway, the aroA-encoded 5-enolpyruvylshikimate-3-phosphate synthase from Mycobacterium smegmatis (MsEPSPS). Combining gene knockout experiments and kinetic assays, we established a causal link between aroA gene essentiality and the biological function of EPSPS protein, which we advocate is an indispensable step for target validation. Moreover, we characterized MsEPSPS vulnerability under different nutritional conditions and found it is a vulnerable target only when M. smegmatis is grown under poor nutritional conditions without supplementation with aromatic amino acids. Based on our findings, we suggest that gene essentiality information should be obtained from gene knockout experiments and not knockdown approaches, as even low levels of a protein after gene silencing can lead to a different growth phenotype when compared to that under its complete absence, as was the case with aroA and MsEPSPS in our study.

microbiology↗

bioRxiv2020

Whole-body integration of gene expression and single-cell morphology

Animal bodies are composed of hundreds of cell types that differ in location, morphology, cytoarchitecture, and physiology. This is reflected by cell type-specific transcription factors and downstream effector genes implementing functional specialisation. Here, we establish and explore the link between cell type-specific gene expression and subcellular morphology for the entire body of the marine annelid Platynereis dumerilii. For this, we registered a whole-body cellular expression atlas to a high-resolution electron microscopy dataset, automatically segmented all cell somata and nuclei, and clustered the cells according to gene expression or morphological parameters. We show that collective gene expression most efficiently identifies spatially coherent groups of cells that match anatomical boundaries, which indicates that combinations of regionally expressed transcription factors specify tissue identity. We provide an integrated browser as a Fiji plugin to readily explore, analyse and visualise multimodal datasets with remote on-demand access to all available datasets.

cell biology↗

bioRxiv2020

Transcytosis via the late endocytic pathway as a cell morphogenetic mechanism

Plasma membranes fulfil many physiological functions. In polarized cells, different membrane compartments take on specialized roles, each being allocated correct amounts of membrane. The Drosophila tracheal system, an established tubulogenesis model, contains branched terminal cells with subcellular tubes formed by apical plasma membrane invagination. We show that apical endocytosis and late endosome-mediated trafficking determine the membrane allocation to the apical and basal membrane domains. Basal plasma membrane growth stops if endocytosis is blocked, whereas the apical membrane grows excessively. Plasma membrane is initially delivered apically, and then continuously endocytosed, together with apical and basal cargo. We describe an organelle carrying markers of late endosomes and multivesicular bodies (MVBs) that is abolished by inhibiting endocytosis, and which we suggest acts as transit station for membrane destined to be redistributed both apically and basally. This is based on the observation that disrupting MVB formation prevents growth of both compartments.

cell biology↗