Biology subjects

Wolff, N.

Publications and source records attributed to Wolff, N..

16 recordsLinked to original sources

bioRxiv2026

Divergent Pontine and Cerebellar Pathology in Preterm Infants With Necrotizing Enterocolitis

Importance: Preterm survivors of necrotizing enterocolitis (NEC) face substantial neurodevelopmental impairment, but the regional biology and timing of associated brain abnormalities remain poorly defined. Objective: To define the regional, cellular, molecular, and temporal features of NEC-associated brain pathology. Design: Prospective multimodal clinical cohort study (2012-2024), complemented by postmortem tissue analyses. Setting: Level IV neonatal intensive care unit at Children's National Hospital, Washington, DC. Participants: Of 400 infants screened, 253 preterm infants born before 37 weeks' gestation (128 with NEC and 125 without NEC) were included across neuroimaging, plasma metabolomic, and postmortem cohorts. Exposures: Medical or surgical NEC (modified Bell stage [≥]II). Main Outcomes and Measures: Primary outcomes were term-equivalent magnetic resonance imaging (MRI) abnormalities and serial ultrasound hindbrain growth; secondary outcomes were postmortem histopathology, brain and intestinal transcriptomics, and plasma metabolomics. Results: Among 179 infants with term-equivalent MRI (89 NEC, 90 controls; 102 [57.0%] male; mean [SD] gestational age, 26.3 [2.2] weeks), NEC was associated with a higher prevalence of pontine abnormalities (12.4% vs 1.1%; adjusted prevalence ratio, 9.14; 95% CI, 1.16-71.92), alongside white matter, callosal, and cerebellar abnormalities. In postmortem tissue (n = 27), white matter pathology qualitatively resembled that of prematurity, whereas the hindbrain showed distinct regional phenotypes. The cerebellum exhibited external granular layer contraction (42% reduction; P = .04), while the pons showed neuronal injury with increased morphological apoptotic burden (P [≤] .05). Brain and intestinal transcriptomics (n = 14), complemented by plasma metabolomics (n = 29), revealed divergent inflammatory and metabolic signatures. The pons showed increased neuroinflammatory and reduced mitochondrial programs, whereas the cerebellum showed reduced metabolic and cell-cycle programs alongside circulating lysophospholipid depletion. Serial ultrasonography (n = 159), anchored to the cohort mean NEC onset age of 29 weeks' postmenstrual age, identified earlier cerebellar dimensional deficits (P = .015) and later pontine growth deceleration (P < .001). Conclusions and Relevance: In this cohort study, NEC-associated hindbrain pathology showed asynchronous growth patterns accompanied by distinct cellular and molecular phenotypes. These findings support investigation of regional vulnerability and stage-specific neuroprotection; individual injury timing and causal mechanisms remain unresolved.

neuroscience↗

bioRxiv2026

Developmental Arrest Associated with Altered Cerebellar Metabolism in Sudden Infant Death Syndrome

BackgroundEffective autoresuscitation during hypoxic stress demands the cerebellum integrate autonomic and arousal responses. It remains unknown if the SIDS cerebellum possesses the metabolic stability and developmental maturity to sustain this function. We aimed to define if cerebellar dysfunction constitutes a silent failure point within the central respiratory network. MethodsWe performed multi-omic integration of RNA-sequencing, targeted metabolomics, and quantitative histology on postmortem cerebellar tissue from SIDS infants and age-matched controls. Cross-omic concordance analysis mapped the relationship between metabolite abundance and the transcriptional directionality of corresponding metabolic enzymes. ResultsThe SIDS cerebellum revealed a distinct profile defined by neuroinflammation and altered GABA and glutamate metabolism. Targeted metabolomics confirmed a metabolic imbalance with significantly elevated glutamate and GABA (P < 0.05). Quantitative histology exposed concurrent developmental arrest; persistent external granule layers highlighted morphological immaturity, explaining the failure to mount effective compensatory responses. ConclusionsMetabolic pathology in the SIDS cerebellum is intrinsically linked to structural immaturity. This developmental arrest creates a compromised environment lacking the metabolic competence to support neural homeostasis, preventing critical arousal responses required for survival. ImpactO_LIMulti-omic and neuropathological analysis reveal that structural immaturity in SIDS cerebellum is directly linked to neuroinflammation and metabolic excitotoxicity. C_LIO_LIDevelopmental arrest leaves the tissue metabolically incompetent to support the neural homeostasis required for infant survival during hypoxic stress. C_LIO_LIThis study shifts the focus of SIDS pathology beyond traditional brainstem mechanisms by establishing the cerebellum as a critical, point of failure within the central respiratory network, providing a direct link between morphological delay and functional neurochemical disruption C_LIO_LIThese findings offer translatable paradigm for understanding SIDS vulnerability and identify specific metabolic targets for future diagnostic risk screening and therapeutic interventions. C_LI

neuroscience↗

bioRxiv2026

Structural insights into the inactive state of the adhesion GPCR ADGRV1

Adhesion G protein-coupled receptors (aGPCRs) are involved in numerous physiological processes, including cell-cell and cell-matrix interactions, and are associated with several human diseases. ADGRV1 is a member of the aGPCR family and plays a significant role in the sensorineural systems. Mutations of ADGRV1 are linked to the Usher syndrome, a genetic disorder causing deafness and blindness in human. However, the molecular mechanisms that control the activity of ADGRV1 remain unclear. In this study, we present the high-resolution cryo-electron microscopy structure of the inactive ADGRV1 receptor in complex with the nanobody RE02, providing detailed insights into its transmembrane domain, intracellular loop conformations and the inactive orthosteric site. Functional cellular assays revealed that ADGRV1 exhibits a weak constitutive activation independent of the tethered agonist peptide, primarily coupling with Gi proteins. These findings suggest that ADGRV1 may employ an alternative activation mechanism, distinct that from other aGPCRs reported so far. Our structural analysis highlights that ADGRV1 does not follow the conventional tethered agonist activation mechanism. This is due to the divergent sequence of its tethered agonist peptide, as well as the lack of residues critical for conformational transitions toward the active state in other aGPCRs. Moreover, the large intracellular loop 3 (ICL3) adopts a closed conformation, tightly packed against the transmembrane region of ADGRV1. This suggests that the ICL3 loop can compete with G-protein binding, ultimately acting as an additional barrier for ADGRV1 activation. Significance StatementAdhesion G protein-coupled receptors (aGPCRs) regulate essential processes such as cell communication and sensory function, yet the mechanisms controlling many family members remain poorly understood. We report the first high-resolution cryo-electron microscopy structure of the human receptor ADGRV1, a protein linked to Usher syndrome, a major genetic cause of deafness and blindness. Structural and functional analyses reveal that ADGRV1 displays weak constitutive signaling and likely operates through an activation mechanism distinct from the canonical tethered agonist model that defines most aGPCRs. Unique structural features, including a closed intracellular loop (ICL3) that may limit G-protein engagement, suggest an alternative regulatory strategy. These findings expand the conceptual framework of aGPCR activation and provide a foundation for understanding ADGRV1 function in sensory physiology and disease.

biochemistry↗

bioRxiv2025

Intrinsic Gestational Timing Governs Human Cerebellar Development After Preterm Birth

Intrinsic programs shape brain maturation, yet which are perturbed by prematurity, and the molecular pathways involved remain unknown. The human cerebellum serves as a paradigm of extrauterine development; its accelerated growth and circuit formation align with the third trimester, a period disrupted by preterm delivery. Through multimodal datasets encompassing in vivo neuroimaging and neurodevelopmental outcomes with postmortem spatial-transcriptomic and histopathological profiling, we show that prematurity diverts the cerebellar developmental trajectory. Cerebellar growth and functional outcomes scaled with gestational age, despite modifying perinatal exposures. Spatially resolved developmental programs underlying macroscopic trajectories were marked by incomplete granule cell maturation and impaired Purkinje cell structural refinement, indicating lineage-specific developmental asynchrony. Thus, prematurity constitutes biologically displaced maturation, in which infants of equivalent post-menstrual age occupy divergent developmental states.

neuroscience↗

bioRxiv2025

Prematurity Reprograms Cerebellar Development and Long-Term Behavior

Preterm survivors often develop motor and socio-cognitive impairments that implicate altered cerebellar development, yet the underlying mechanisms remain poorly understood. A key challenge is that prematurity involves overlapping perinatal insults that converge on the developing brain, making their individual effects difficult to disentangle. Here, we model two major prematurity-associated insults, maternal immune activation (MIA) and neonatal hypoxia (Hx), in mice. By controlling timing and sequence, we define how these insults shape cerebellar assembly during rapid maturation. Comparative analysis with human tissue confirmed that these insults recapitulate key features of the human preterm cerebellum, establishing the translational validity of this model for dissecting insult-specific outcomes. Behavioral and kinematic profiling revealed divergent motor and social phenotypes, which we traced to insult-specific cerebellar remodelling. Hypoxia compromised both granule cell maturation in the internal granule layer and the principal excitatory afferents to Purkinje cells, a circuit state that manifested as impaired motor execution and stereotyped, sensory-disengaged social investigation. Maternal immune activation, by contrast, expanded the granule cell progenitor layer and reduced Purkinje cell dendritic complexity, a phenotype that preserved social preference but reorganized the kinematic structure of social investigation. When hypoxia followed maternal immune activation, it acted on this primed substrate to produce a distinct state in which the features established by prior inflammation were compounded by granule cell proliferative arrest, progressive mitochondrial dysfunction, and aberrant, hyper-interactive social investigation. Together, these findings reframe prematurity-associated insults as cerebellar reprogramming events shaped by both the identity and sequence of insults, linking distinct mechanistic substrates to divergent neurodevelopmental outcomes.

neuroscience↗

bioRxiv2025

HTRF-based identification of small molecules targeting SARS-CoV-2 E protein interaction with ZO-1 PDZ2

The SARS-CoV-2 E protein through its C-terminal PDZ-binding motif (PBM) interacts with several host PDZ-containing proteins, including the ZO-1 protein via its PDZ2 domain, thereby contributing to viral pathogenesis. Targeting this interaction represents a potential therapeutic strategy. In this study, we determined the X-ray structure of the E PBM peptide in complex with the ZO-1 PDZ2 domain at 1.7 [A] resolution. The structure revealed a domain-swapped dimer conformation of ZO-1 PDZ2, with the E PBM peptide conventionally bound within the PDZ domains canonical binding groove exhibiting key interactions characteristic of type II PBM-PDZ interactions. To identify potential inhibitors of the E PBM/ZO-1 PDZ2 interaction, we performed a HTRF screening using a protein-protein interaction-focused library of 1,000 compounds. This led to the identification of 36 hits that disrupted this interaction. Subsequent cytotoxicity and dose- response assays narrowed the selection to 14 promising compounds. Docking simulations showed that some compounds bind within or near the PBM-binding pocket, supporting a competitive mechanism of interaction inhibition, while others bind at a central interface between the two PDZ monomers, suggesting an inhibition of dimerization, which in turn prevents PBM binding. Thus, the ZO-1 PDZ2-E PBM interaction can be inhibited through both direct and indirect mechanisms. Finally, antiviral assays using a NanoLuciferase-expressing recombinant SARS-CoV-2 demonstrated that one compound, C19, significantly reduced viral replication, highlighting its potential as a candidate for further therapeutic development. HighlightsO_LICrystal structure reveals the binding determinant of E protein PBM to ZO-1 PDZ2 dimer C_LIO_LIHTRF screening identified 36 inhibitors of the E-ZO-1 protein interaction C_LIO_LIDocking revealed dual mechanisms: PBM groove binding and dimer interface disruption C_LIO_LICompound C19 reduced SARS-CoV-2 replication in a NanoLuc reporter assay C_LIO_LITargeting E-ZO-1 interaction may prevent barrier loss and systemic COVID-19 effects C_LI Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/665136v1_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@1f900bcorg.highwire.dtl.DTLVardef@9f470aorg.highwire.dtl.DTLVardef@f0ec19org.highwire.dtl.DTLVardef@11c9115_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

bioRxiv2025

Cerebellum and Plasma Metabolomics Identify Sepsis Biomarkers and MSC-sEV-Mediated Rescue

Septic encephalopathy (SE) is a severe complication of sepsis, characterized by neuroinflammation and metabolic dysfunction, with the cerebellum among the most vulnerable brain regions. Advances in the field have been constrained by the lack of reliable biomarkers for SE detection, incomplete mapping of cerebellar metabolic alterations in SE, and limited insight into the therapeutic mechanisms of human mesenchymal stem cell (MSC)-derived small extracellular vesicle (sEV) therapy. To overcome these challenges, we used a murine sepsis model and conducted integrated metabolomic analyses of cerebellar tissue and plasma, with and without MSC-sEV administration. Cross-compartment analyses identified six plasma metabolites with strong diagnostic potential in mice, three of which (n-acetylputrescine, aspartic acid, and cystathionine) were also observed in the plasma of human septic patients, supporting their promise as translatable biomarker candidates. Sepsis triggered profound cerebellar metabolic dysfunction, suppression of oxidative energy metabolism, and redox imbalance. MSC-sEVs attenuated these disturbances via their bioactive cargo, restoring cellular energetics and reestablishing antioxidant balance. Collectively, these results highlight cross-species plasma biomarkers for SE diagnosis, delineate key cerebellar metabolic mechanisms in SE, and demonstrate therapeutic modulation by human MSC-sEVs.

neuroscience↗

bioRxiv2024

The SARS-CoV-2 envelope PDZ Binding Motif acts as a virulence factor disrupting host's epithelial cell-cell junctions

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the virus responsible for the COVID-19 pandemic, has significantly impacted global health, emphasizing the need to understand its pathogenicity and virulence mechanisms. SARS-CoV-2 disrupts the alveolar epithelial barrier and exacerbates airway inflammation, leading to acute respiratory failure, but the molecular details remain unclear. Additionally, SARS-CoV-2 infection causes neurological symptoms, potentially due to its weakly understood ability to cross the blood-brain barrier. The viral multifunctional Envelope (E) protein is crucial for its virulence, playing a key role in virus assembly, budding, and release. The E protein contains a PDZ-binding motif (PBM) that interacts with host PDZ domain-containing proteins, potentially affecting host signaling pathways and contributing to pathogenicity. This study focuses on the E protein PBM and its role in virulence, disrupting respiratory epithelial barriers and exacerbating airway inflammation. We generated recombinant mutant viruses lacking the PBM and conducted both in vitro and in vivo experiments to elucidate its impact on viral fitness, pathogenicity, and effects on the epithelial integrity. In vitro, the viral mutants showed delayed replication and reduced cytopathic effects. In vivo, experiments with hamsters revealed that PBM-deficient viruses caused less weight loss, lower viral loads, and reduced inflammation, indicating decreased pathogenicity. Histological analyses confirmed less airway damage in these hamsters compared to those infected with the wild-type virus. Additionally, PBM-deficient viruses had impaired interactions with tight junction proteins like ZO-1, a PDZ-containing protein, crucial for maintaining epithelial barrier integrity. Our findings also demonstrate that the PBM does not play a significant role in neuroinvasion during the acute phase of infection, as evidenced by comparable viral RNA loads across brain regions in infected hamsters, regardless of PBM presence. Histopathological and transcriptomic analyses further support this observation, suggesting that the PBM primarily affects specific epithelial barriers. Additionally, RNA-seq analysis on lung and brainstem from infected hamsters reveals that the PBM modulates inflammatory and immune responses, with a stronger impact in lung tissue than in the brainstem. PBM-deficient viruses induce lower levels of inflammation and cytokine expression, suggesting PBMs specific role in enhancing viral pathogenicity through the activation of pathways such as NF-{kappa}B and TNF. Thus, the E protein PBM plays a critical role in SARS-CoV-2s fitness, virulence, and pathogenicity, through the disruption of cell junctions and inflammation, underscoring its potential as a target for therapeutic interventions.

pathology↗

bioRxiv2023

Bloodmeal metabarcoding of the argasid tick (Ornithodoros turicata Duges) reveals extensive vector-host associations

Molecular methods to understand host feeding patterns of arthropod vectors are critical to assess exposure risk to vector-borne disease and unveil complex ecological interactions. We build on our prior work discovering the utility of PCR-Sanger sequencing bloodmeal analysis that work remarkably well for soft ticks (Acari: Argasidae), unlike for hard ticks (Acari: Ixodidae), thanks to their unique physiology that retains vertebrate DNA from prior bloodmeals viable for years. Here, we capitalize on this feature and apply bloodmeal metabarcoding using amplicon deep sequencing to identify multiple host species in individual Ornithodoros turicata soft ticks collected from two natural areas in Texas, United States. Of 788 collected O. turicata, 394 were evaluated for bloodmeal source via metabarcoding, revealing 27 different vertebrate host species (17 mammals, 5 birds, 1 reptile, and 4 amphibians) fed upon by 274 soft ticks. Information on multiple hosts for individual O. turicata was derived from 168 of these (61%). Metabarcoding revealed more mixed vertebrate bloodmeals in O. turicata previously processed using Sanger sequencing. These data reveal wide host range of O. turicata and demonstrate the value of bloodmeal metabarcoding for understanding the ecology for known and potential tick-borne pathogens circulating among humans, domestic animals and wildlife such as relapsing fever caused by Borrelia turicatae. Our results also document, for the first time an off-host soft tick collected to have evidence of prior feeding on wild pig which is a critical observation in the context of the threat of enzootic transmission of African swine fever virus if it were introduced to the US. This research enhances our understanding of vector-host associations and offers a promising perspective for biodiversity monitoring and disease control strategies.

ecology↗

bioRxiv2023

Interactions of the Protein Tyrosine Phosphatase PTPN3 with Viral and Cellular Partners through its PDZ Domain: Insights into Structural Determinants and Phosphatase Activity

The human protein tyrosine phosphatase non-receptor type 3 (PTPN3) is a phosphatase containing a PDZ (PSD-95/Dlg/ZO-1) domain that has been found to play both tumor-suppressive and tumor-promoting roles in various cancers, despite limited knowledge of its cellular partners and signaling functions. Notably, the high-risk genital human papillomavirus (HPV) types 16 and 18 and the hepatitis B virus (HBV) target the PDZ domain of PTPN3 through PDZ-binding motifs (PBMs) in their E6 and HBc proteins respectively. This study focuses on the interactions between the PTPN3 PDZ domain (PTPN3-PDZ) and PBMs of viral and cellular protein partners. The solved X-ray structures of complexes between PTPN3-PDZ and PBMs of E6 of HPV18 and the tumor necrosis factor-alpha converting enzyme (TACE) reveal two novel interactions. We provide new insights into key structural determinants of PBM recognition by PTPN3 by screening the selectivity of PTPN3-PDZ recognition of PBMs, and by comparing the PDZome binding profiles of PTPN3-recognized PBMs and the interactome of PTPN3-PDZ. The PDZ domain of PTPN3 was known to auto-inhibit the proteins phosphatase activity. We discovered that the linker connecting the PDZ and phosphatase domains is involved in this inhibition, and that the binding of PBMs does not impact this catalytic regulation. Overall, the study sheds light on the interactions and structural determinants of PTPN3 with its cellular and viral partners, as well as on the inhibitory role of its PDZ domain on its phosphatase activity.

biophysics↗

bioRxiv2022

Neuroinvasion and anosmia are independent phenomena upon infection with SARS-CoV-2 and its variants

SUMMARYAnosmia was identified as a hallmark of COVID-19 early in the pandemic, however, with the emergence of variants of concern, the clinical profile induced by SARS-CoV-2 infection has changed, with anosmia being less frequent. Here, we assessed the clinical, olfactory and neuroinflammatory conditions of golden hamsters infected with the original Wuhan SARS-CoV-2 strain, its isogenic ORF7-deletion mutant and three variants: Gamma, Delta, and Omicron/BA.1. We show that infected animals developed a variant-dependent clinical disease including anosmia, and that the ORF7 of SARS-CoV-2 contributes to the induction of olfactory dysfunction. Conversely, all SARS- CoV-2 variants were found to be neuroinvasive, regardless of the clinical presentation they induce. Taken together, this confirms that neuroinvasion and anosmia are independent phenomena upon SARS-CoV-2 infection. Using newly generated nanoluciferase-expressing SARS-CoV-2, we validated the olfactory pathway as a major entry point into the brain in vivo and demonstrated in vitro that SARS-CoV-2 travels retrogradely and anterogradely along axons in microfluidic neuron-epithelial networks. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=151 HEIGHT=200 SRC="FIGDIR/small/505985v2_ufig1.gif" ALT="Figure 1"> View larger version (58K): org.highwire.dtl.DTLVardef@8225ceorg.highwire.dtl.DTLVardef@80342aorg.highwire.dtl.DTLVardef@e0dfd1org.highwire.dtl.DTLVardef@1861e13_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2021

Interactions of SARS-CoV-2 protein E with cell junctions and polarity PDZ-containing proteins

The C-terminus of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protein E contains a PBM (PDZ binding motif) targeting PDZ (PSD-95/Dlg/ZO-1) domains identical to the PBM of SARS-CoV. The latter is involved in the pathogenicity of the virus. Recently, we identified ten human PDZ-containing proteins showing significant interactions with SARS-CoV-2 protein E PBM. We selected several of them involved in cellular junctions and cell polarity (TJP1, PARD3, MLLT4, LNX2) and MPP5/Pals1 previously shown to interact with SARS-CoV E PBM. Targeting cellular junctions and polarity components is a common strategy by viruses to hijack cell machinery to their advantage. In this study, we showed that these host PDZ domains TJP1, PARD3, MLLT4, LNX2 and MPP5/PALS1 interact in a PBM-dependent manner in vitro and colocalize with the full-length E protein in cellulo, sequestrating the PDZ domains to the Golgi compartment. We solved three crystal structures of complexes between human LNX2, MLLT4 and MPP5 PDZs and SARS-CoV-2 E PBM highlighting its binding preferences for several cellular targets. Finally, we showed different affinities for the PDZ domains with the original SARS-CoV-2 C-terminal sequence containing the PBM and the one of the beta variant that contains a mutation close to the PBM. The acquired mutations in E protein localized near the PBM might have important effects both on the structure and the ion-channel activity of the E protein and on the host machinery targeted by the variants during the infection.

biochemistry↗

bioRxiv2021

PDZ-containing proteins targeted by the ACE2 receptor

Angiotensin converting enzyme 2 (ACE2) is a main receptor for SARS-CoV-2 entry to the host cell. Indeed, the first step in viral entry is the binding of the viral trimeric spike protein to ACE2. Abundantly present in human epithelial cells of many organs, ACE2 is also expressed in the human brain. ACE2 is a type I membrane protein with an extracellular N-terminal peptidase domain and a C-terminal collectrin-like domain that ends with a single transmembrane helix and an intracellular 44-residues segment. This C-terminal segment contains a PDZ-binding motif (PBM) targeting protein interacting domains called PSD-95/Dlg/ZO-1 (PDZ). Here, we identified the human PDZ specificity profile of the ACE2 PBM using the high throughput holdup assay and measuring the binding intensities of the PBM of ACE2 against the full human PDZome. We discovered 14 human PDZ binders of ACE2 showing significant binding with dissociation constants values ranging from 3 to 81 M. NHERF, SHANK, and SNX27 proteins found in this study are involved in protein trafficking. The PDZ/PBM interactions with ACE2 could play a role on ACE2 internalization and recycling that could benefit for the virus entry. Interestingly, most of the ACE2 partners we identified are expressed in neuronal cells, such as SHANK and MAST families, and modifications of the interactions between ACE2 and these neuronal proteins may be involved in neurological symptoms of COVID-19.

biochemistry↗

bioRxiv2021

Host PDZ-containing proteins targeted by SARS-Cov-2

Small linear motif targeting protein interacting domains called PDZ have been identified at the C-terminus of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) proteins E, 3a, and N. Using a high-throughput approach of affinity-profiling against the full human PDZome, we identified sixteen human PDZ binders of SARS-CoV-2 proteins E, 3A and N showing significant interactions with dissociation constants values ranging from 3 M to 82 M. Six of them (TJP1, PTPN13, HTRA1, PARD3, MLLT4, LNX2) are also recognized by SARS-CoV while three (NHERF1, MAST2, RADIL) are specific to SARS-CoV-2 E protein. Most of these SARS-CoV-2 protein partners are involved in cellular junctions/polarity and could be also linked to evasion mechanisms of the immune responses during viral infection. Seven of the PDZ-containing proteins among binders of the SARS-CoV-2 proteins E, 3a or N affect significantly viral replication under knock-down gene expression in infected cells. This PDZ profiling identifying human proteins potentially targeted by SARS-CoV-2 can help to understand the multifactorial severity of COVID19 and to conceive effective anti-coronaviral agents for therapeutic purposes.

biochemistry↗

bioRxiv2020

Interactomic affinity profiling by holdup assay: acetylation and distal residues impact the PDZome-binding specificity of PTEN phosphatase

Protein domains often recognize short linear protein motifs composed of a core conserved consensus sequence surrounded by less critical, modulatory positions. Here we used an accurate experimental approach combining high-throughput holdup chromatographic assay and fluorescence polarization to measure quantitative binding affinity profiles of the PDZ domain-binding motif (PBM) of PTEN phosphatase towards the 266 known human PDZ domains. Inclusion of N-terminal flanking residues, acetylation or mutation of a lysine at a modulatory position significantly altered the PDZome-binding profile of the PTEN PBM. A specificity index is also introduced to quantify the specificity of a given PBM over the complete PDZome. Our results highlight the impact of modulatory residues and post-translational modifications on PBM interactomes and their specificity.Competing Interest StatementThe authors have declared no competing interest.View Full Text

biophysics↗

bioRxiv2018

Synchrotron FTIR and Raman spectroscopy provide unique spectral fingerprints for Arabidopsis floral stem vascular tissues

Cell walls are highly complex structures that are modified during plant growth and development. For example, the development of phloem and xylem vascular cells, which participate in the transport of sugars and water as well as support, can be influenced by cell-specific cell wall composition. Here, we used synchrotron radiation-based infrared (SR-FTIR) and Raman spectroscopy to analyze the cell wall composition of wild-type and double mutant sweet11-1sweet12-1, which impairs sugar transport, Arabidopsis floral stem vascular tissue. The SR-FTIR spectra showed that in addition to modified xylem cell wall composition, phloem cell walls in the double mutant line were characterized by modified hemicellulose composition. Moreover, combining Raman spectroscopy with a Classification and Regression Tree (CART) method identified combinations of Raman shifts that could distinguish xylem vessels and fibers. Additionally, the disruption of SWEET11 and SWEET12 genes impacts xylem cell wall composition in a cell-specific manner, with changes in hemicelluloses and cellulose observed at the xylem vessel interface. These results suggest that the facilitated transport of sugars by transporters that exist between vascular parenchyma cells and conducting cells is important to ensuring correct phloem and xylem cell wall composition.\n\nHighlightCombining vibrational spectroscopy techniques and multivariate analysis shows that the disruption of SWEET genes impacts phloem cell wall composition and that the effect on xylem cell wall composition is cell-specific.

plant biology↗