Biology subjects

Di Maio, A.

Publications and source records attributed to Di Maio, A..

15 recordsLinked to original sources

bioRxiv2026

Mechanism of spike opening in a mammalian gammacoronavirus

Coronavirus spike proteins mediate receptor binding and fusion and are key determinants of viral host range. To bind protein receptors, some CoV spikes undergo conformational changes termed opening, which expose the receptor-binding surface. Yet, the prerequisites and mechanism of spike opening remain poorly understood, especially outside of beta-CoVs, and many CoV spikes have been observed only in the closed conformation. The receptor specificities of gamma-CoVs, for which birds are natural hosts, await in-depth characterisation and their spikes have not been observed to open. Here, we report structures of the spike from an unusual mammalian gamma-CoV isolated from a beluga whale (BwCoV), in closed and open conformations, the latter with two S1B domains erect. BwCoV spike opening is associated with changes throughout S1 that resemble those observed in beta-CoV spikes and similarly propagate into destabilisation of the fusogenic S2 core. Furthermore, the BwCoV-S structure contains an additional density likely corresponding to a fatty acid, consistent with lipid binding stabilising the closed conformation through a pocket distinct from that identified for beta-CoVs. These structural insights reveal conserved principles regulating spike dynamics across coronavirus genera and support lipid binding as a potential modulatory mechanism of spike opening.

biochemistry↗

bioRxiv2026

Mutations in severe human H5N1 cases facilitate evasion from human mucus and antivirals

In late 2024, two individuals in Canada and the United States were treated in intensive care for acute respiratory distress caused by infection with the avian Influenza A Virus H5N1 2.3.4.4b genotype D1.1. Viral sequence data obtained from sampling these patients indicated mixed alleles at haemagglutinin (HA) positions 190 and 226. Mutations at these positions are key determinants of HA usage of 2,6-linked sialic acids (SA), the most abundant influenza receptors in human upper respiratory tracts. Thus, these mutations raised concerns about human adaptation and pandemic potential of the H5N1 virus. In this study, we investigated the impact of the mutations at residues 190 and 226 in H5 HA. We studied the receptor binding properties, cell entry phenotypes and fitness impacts of the mutations using recombinant proteins, pseudotyped lentiviruses, and in the context of influenza viruses using reverse genetics. The mutations did not confer any detectable 2,6-linked sialic acid receptor usage either alone or in combination. Rather, viruses carrying these mutations exhibit weakened binding towards 2,3-linked sialic acid receptors. This correlated with an enhanced capacity to evade human airway mucus, and a reduced susceptibility to oseltamivir and zanamivir. This research underscores that in addition to the way HA interacts with SA as entry receptors, other factors that impact the HA/NA balance might influence the evolutionary trajectory of a zoonotic virus in the human respiratory tract. This study presents a new paradigm for the evolutionary drivers of HA, where reduced sialic acid binding can serve as an advantage for escape from host barriers and antivirals.

microbiology↗

bioRxiv2026

A long-chain heparan sulfate capture mechanism directs paracrine GDNF-GFRα1 signalling through RET

The receptor tyrosine kinase RET is activated by GDNF and GFR1 together as a bipartite ligand, driving receptor activation and signalling in developmental and neuroprotective contexts. Evidence from developmental and cell models has suggested that heparan sulfate (HS) functions as a fourth component in RET signalling by binding to GDNF, but the molecular details remain unclear. Here, we present the cryo-EM structure of the heterohexameric RET:GDNF:GFR1 complex with a fully resolved heparin ligand, revealing an unexpected extended HS binding site spanning all three proteins. The architecture of the complex and binding mode of the HS chain in this complex enables the formation of a higher order 4:4:4 assembly bound to a single 30-saccharide HS chain which bridges two intimately bound complexes. This multi-protein interface selectively binds the highly sulfated domains of HS over other GAG classes, and is essential for RET activation in trans with soluble GFR1, but not in cis when GFR1 is membrane-bound. Our data suggest that HS shapes the dynamics of RET signalling at every stage, from ligand diffusion to signalling complex formation. Thus, GDNF-GFRa1 paracrine signalling reveals a surprising dependence for long-chain GAG function in which the glycan engages in both receptor complex assembly and clustering.

biochemistry↗

bioRxiv2026

Embryonic depletion of D-aspartate perturbs NMDA receptor-dependent long-term potentiation in the hippocampus of juvenile mice

D-Aspartate (D-Asp) is an endogenous D-amino acid that exhibits a pronounced developmental peak in the mammalian brain, suggesting a potential regulatory role in glutamatergic signaling and neurodevelopment. Disruption of D-Asp homeostasis has been associated with neuropsychiatric disorders characterized by early-life circuit vulnerability, including schizophrenia and autism spectrum disorders. However, its functional impact to hippocampal physiology remains incompletely defined. Here, we investigated how constitutive D-Asp depletion affects synaptic function in the hippocampal CA1 region of Ddo-knock-in (Ddo-KI) mice, in which zygotic overexpression of the D-Asp-degrading enzyme, D-aspartate oxidase (DASPO), results in embryonic and persistent D-Asp deficiency. Electrophysiological recordings were performed in acute hippocampal slices from male and female mice at postnatal day 30 (P30) and day 60 (P60). Basal synaptic transmission, assessed through paired-pulse ratio and spontaneous excitatory/inhibitory events, was unaltered between genotypes, indicating preserved presynaptic release probability and overall excitation/inhibition balance. In contrast, NMDA receptor (NMDAR)-dependent synaptic plasticity was selectively altered, as theta-burst stimulation induced significantly greater long-term potentiation (LTP) in juvenile P30 Ddo-KI mice, whereas this difference was no longer observed at P60. Consistently, patch-clamp recordings revealed a reduced AMPAR/NMDAR ratio in P30 Ddo-KI males, suggesting an increased relative contribution of NMDAR-mediated currents. Importantly, acute bath application of exogenous D-Asp restored LTP to wild-type levels, demonstrating rapid reversibility and supporting a model of homeostatic receptor rebalancing rather than irreversible circuit alterations. Biochemical assays confirmed significantly increased DASPO activity and reduced D-Asp levels in Ddo-KI mice. However, these parameters remained stable between P30 and P60, indicating that the age-dependent plasticity phenotype is unlikely to arise from progressive biochemical changes. Together, these findings indicate that developmental D-Asp deficiency induces a transient, juvenile-specific alteration characterized by enhanced NMDAR-dependent synaptic plasticity, which can be rapidly normalized upon D-Asp re-exposure.

neuroscience↗

bioRxiv2026

M1 protein expression determines niche-specific spread of Streptococcus pyogenes

Invasive infections with Streptococcus pyogenes account for significant mortality. Cell surface M protein is believed to be essential for S. pyogenes virulence, with critical roles in dissemination and immune evasion. In contrast, the role of secreted M protein in infection is less clear. Here, we assessed the role of M protein in streptococcal colonisation, persistence, and invasion in respiratory and soft tissue murine infection models, and report that while cell-surface M protein is required to establish nasopharyngeal infection, it does not drive invasive infection. Cell-surface M protein was important for binding of major host matrix proteins and growth in immune human blood, but soluble M protein was the predominant determinant of lymphatic survival, tissue spread, and systemic infection in mice. A mutant emm1 strain which only expresses secreted M protein exhibited enhanced survival in the lymph node niche and overall competitive advantage over the wildtype parent strain in co-infections. Absence of M protein at the bacterial cell surface led to enhanced hyaluronan binding, providing explanation for homing to the draining lymph node. Together, these findings highlight potential nuance in the role of M protein that may impact vaccine approaches targeting M protein. Author SummaryS. pyogenes is a significant cause of illness, both mild and lethal, worldwide. Despite this, there are currently no approved vaccines. Many vaccine candidates are based on the M protein, a surface expressed anti-phagocytic factor that is thought to be critical for the ability of S. pyogenes to evade the host immune system. The unexpected selection of an M1 protein mutant strain following in vivo soft tissue infection raised many questions for us. If M protein is meant to be the critical factor in avoiding immune killing, how was this strain able to persist? One explanation could be that, although the strain was negative for M1 protein on the bacterial surface, it still secreted a truncated version of the protein with potential inflammatory effects. Importantly, the strain was selected in the draining lymph node pointing to a niche-specific advantage. We showed that cell surface-associated M1 protein, although required to establish nasopharyngeal infection, was not required in soft tissue infection, and that expression of a soluble, truncated form of M1 protein gave a survival advantage over the wild-type strain expressing cell wall-associated M1 protein. Furthermore, the absence of cell surface M protein led to enhanced hyaluronan binding providing explanation for lymphatic niche homing.

microbiology↗

bioRxiv2025

Deep Brain Stimulation rescues the homeostasis disruption of circulating D- and L-amino acids level in men with Parkinson's Disease.

Recent evidence indicates a marked downregulation of circulating D- and L-amino acids involved in regulating glutamatergic NMDAR function in Parkinsons disease (PD) patients compared with matched controls. However, the extent to which disease progression and antiparkinsonian therapies contribute to this dysregulation remains unclear. To address these issues, in the present study we measured by High Performance Liquid Chromatography the concentrations of glutamatergic system-related D- and L-amino acids and their precursors in the plasma of male and female healthy controls (HC) and PD patients across three distinct clinical stages and treatment conditions: (1) early stage L-DOPA naive patients treated with MAO-B inhibitors; (2) mid-stage patients treated with L-DOPA; and (3) advanced stage patients receiving Deep Brain Stimulation in the subthalamic nucleus (STN-DBS) plus L-DOPA. Our results reveal notable reduction of circulating neuroactive D- and L-amino acids exclusively in male PD patients, while female patients exhibit a similar directional trend. In male patients, this dysregulation manifests early, with L-DOPA-naive individuals showing decreased plasma levels of L-glutamate and L-aspartate. In mid-stage L-DOPA-treated PD patients, amino acid reductions extend to L-alanine, L-serine, L-glutamine, L-asparagine, and L-threonine. Remarkably, in advanced PD patients, with a median disease duration of [~] 23 years, STN-DBS normalizes the blood concentrations of these amino acids to those observed in HC. In conclusion, our study highlights the potential of circulating D- and L-amino acid dysregulation as an early biomarker of PD and demonstrates that, in contrast to L-DOPA therapy, the STN-DBS confers systemic metabolic benefits even at advanced stages of the disease.

neuroscience↗

bioRxiv2025

Ultra-performance liquid chromatography-mass spectrometry analysis of post-mortem brain tissue reveals specific amino acid profile dysregulation in Parkinson's Disease and Alzheimer's Disease patients

BackgroundCombined metabolomic and HPLC-based analyses have identified significant metabolic alterations in serum and plasma amino acid levels of Parkinsons disease (PD) patients, underscoring their potential as biomarkers. However, it remains unclear whether these biochemical changes also manifest within the central nervous system or are confined to peripheral metabolism, reflecting systemic metabolic disturbances. MethodsTo address this issue, here we measured the levels of 44 different amino acids in post-mortem brain samples from MPTP-intoxicated, L-DOPA-treated monkeys and PD patients at different Braak Lewy body (LB) stages, compared to their respective controls, through targeted Ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). ResultsIn MPTP-intoxicated monkeys, UPLC-MS revealed significant elevations in GABA, citrulline, threonine, isoleucine, phenylalanine, valine, glycine, and serine in the putamen, whereas we failed to detect alterations in the superior frontal gyrus (SFG). In PD patients, caudate-putamen (CPu) analysis demonstrated consistent serine upregulation across Braak LB stages 3-4 and 6, with stage 6 specifically showing additional proline increases and phosphoethanolamine decreases. Notably, serine was the sole amino acid significantly altered in both the putamen of MPTP-intoxicated monkeys and the CPu of PD patients. No significant amino acid alterations were observed in the SFG of PD patients, mirroring the findings in monkeys. In contrast, Alzheimers disease (AD) patient SFG samples showed significant increases in tryptophan, phenylalanine, threonine, tyrosine, and methionine relative to controls. ConclusionsThese findings demonstrate that cerebral amino acid alterations in PD are region-specific and primarily localized to brain areas receiving nigrostriatal dopaminergic innervation. Moreover, the cortical amino acid profile in AD differs substantially from that in PD, suggesting disease-specific metabolic signatures in distinct neurodegenerative conditions.

neuroscience↗

bioRxiv2025

Pde5a Deficiency Prevents Diet-Induced Obesity via Adipose cAMP-PKA Activation Enhancing Fat Browning

Cyclic nucleotides are critical regulators of adaptive thermogenesis and adipogenesis, with their intracellular levels finely tuned by phosphodiesterases. Phosphodiesterase type 5 (PDE5A) modulates cyclic guanosine monophosphate levels in adipocytes. While PDE5A inhibition has shown promise in patients with diabetes, its role in metabolism remains unclear. Using Pde5a knockout mouse models, we demonstrated that mice lacking Pde5a exhibit enhanced browning of white adipose tissue and reduced hepatic fat content. Following high-fat diet, Pde5a-/- mice are resistant to obesity, displaying improved glucose metabolism and enhanced thermogenesis. These protective effects stem from an early developmental knockdown of Pde5a, leading to a metabolic reprogramming driven by cAMP-PKA pathway activation. The convergence of cGMP and cAMP signaling orchestrates thermogenic and systemic metabolic adaptations. Our findings establish PDE5A as a novel regulator of energy homeostasis, suggesting its inhibition as a valuable adjuvant therapy for metabolic disorders.

cell biology↗

bioRxiv2023

Elucidating the Glycan-Binding Specificity and Structure of Cucumis melo Agglutinin, a New R-Type Lectin

Plant lectins have garnered attention for their roles as laboratory probes and potential therapeutics. Here, we report the discovery and characterization of Cucumis melo agglutinin (CMA1), a new R-type lectin from melon. Our findings reveal CMA1s unique glycan-binding profile, mechanistically explained by its 3D structure, augmenting our understanding of R-type lectins. We expressed CMA1 recombinantly and assessed its binding specificity using multiple glycan arrays, covering 1,046 unique sequences. This resulted in a complex binding profile, strongly preferring C2-substituted, beta-linked galactose (both GalNAc and Fuca1-2Gal), which we contrasted with the established R-type RCA1 lectin. We also report binding of specific glycosaminoglycan subtypes and a general enhancement of binding by sulfation. Further validation using agglutination, thermal shift assays, and surface plasmon resonance confirmed and quantified this binding specificity in solution. Finally, we solved the high-resolution structure of the CMA1 N-terminal domain using X-ray crystallography, supporting our functional findings at the molecular level. Our study provides a comprehensive understanding of CMA1, laying the groundwork for further exploration of its biological and therapeutic potential.

biochemistry↗

bioRxiv2023

Novel multifunctional glycan probes to elucidate specificities of diverse glycan recognition systems

Glycan microarrays of sequence-defined glycans are the most widely used approach for high-throughput studies of interactions of glycans with glycan binding proteins. Currently nitrocellulose (NC) coated or N-hydroxysuccinimide (NHS) functionalized glass slides are the two most commonly used surfaces for immobilizing glycan probes as noncovalent and covalent arrays, respectively. The mode of glycan presentation can have an influence on the microarray readouts and is an important consideration in the glycan recognition knowledgebase. Here we present the development of glycan probes, tagged with a novel type of tri-functional Fmoc-amino-azido (FAA) linker, which can be readily converted into lipid-tagged or amino-terminating glycan probes for generating neoglycolipid (NGL)-based noncovalent arrays as well as covalent arrays. The azido functionality in the FAA glycan probes provides a means to light up the glycans via biorthogonal Click chemistry so that they become scanner-readable on the covalent arrays, which represents an advance in array quality control. Here analyses were carried out with a diverse set of 36 glycan binding proteins (GBPs) to compare the performance of 44 glycans presented in a liposomal formulation as noncovalent arrays on NC coated slides and on two types of NHS slides as covalent arrays. With most of anti-glycan antibodies and plant lectins investigated, there were negligible or subtle differences in the binding detected in different arrays. However, there were some striking differences observed between the covalent and noncovalent arrays. These include binding of Lotus Tetragonolobus Lectin (LTL) on the covalent but not the noncovalent arrays, and a clear preference observed for glycans on the noncovalent array in the binding of adhesins (VP1 proteins) of two human polyomaviruses JCPyV and BKPyV, and the human immune lectins Siglecs 7 and 9. Subtle yet significant differences in the binding to low affinity glycan ligands were also observed with three bacterial toxins in different arrays. These results revealed interesting insights into the binding behaviour of different GBPs on the noncovalent and covalent arrays and highlight the importance to consider different array platforms in elucidating glycan mediated interactions. The FAA glycan probes can be readily rendered fluorescent via Click chemistry in solution, enabling the detection of GBPs at the surface of cells. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=149 SRC="FIGDIR/small/548266v1_ufig1.gif" ALT="Figure 1"> View larger version (66K): org.highwire.dtl.DTLVardef@8f2a49org.highwire.dtl.DTLVardef@1212409org.highwire.dtl.DTLVardef@c4ea39org.highwire.dtl.DTLVardef@1ed6a88_HPS_FORMAT_FIGEXP M_FIG C_FIG A new trifunctional linker can present glycans on different array surfaces for analyses of soluble glycan binding proteins or as fluorescent probes for binding by proteins at the surface of cells.

biochemistry↗

bioRxiv2023

A novel and highly specific Forssman antigen-binding protein from sheep polyomavirus

Polyomaviruses are small, non-enveloped double-stranded DNA viruses of humans and other mammals, birds, and fish. Infections are usually asymptomatic and result in latency, however, some polyomaviruses can induce severe diseases, including cancer, in immunocompromised individuals. Established cellular receptors for polyomavirus infection are sialylated glycolipids (such as gangliosides), membrane proteins, and glycosaminoglycans. Polyomaviruses are usually highly host specific but the exact principles that govern host tropism remain unknown in many cases. Here, glycan array screening shows that the major capsid protein VP1 of sheep polyomavirus (ShPyV) binds to the Forssman glycolipid, an antigen of many vertebrates and a potential tumor marker in humans. Following closer investigation, we can report for the first time that a neutral, non-sialylated glycolipid acts as a polyomavirus receptor. Concurrently, we present the first report of a viral protein that specifically engages the Forssman antigen. We demonstrate that ShPyV VP1 binds to Forssman-positive erythrocytes but not those of human A, B and O blood groups, which is a clear distinction from features thus far described for Forssman lectins. X-ray crystallography and structural analysis of the VP1-Forssman glycan complex define the terminal Forssman disaccharide as the determinant of this protein-receptor interaction. These results strongly suggest that the sheep polyomavirus can use Forssman antigen for infectious cell entry. Furthermore, the ability of ShPyV VP1 to distinguish Forssman-positive from -negative cells may prove useful for monitoring the Forssman- status of normal, preneoplastic and neoplastic cells and tissues and establishing the antigen level as a biomarker. Author summaryElucidation of host cell receptor specificities of viral infection is crucial to understand the pathobiology of associated diseases and develop treatments. However, for many polyomaviruses the receptor engagement as the initial event in infection is poorly understood. In only a few cases polyomavirus tropism has been pinned down to a single type of glycan receptor. While many polyomaviruses utilize sialyl glycans to attach to host cells, the role of non-sialylated glycans as receptors is so far underestimated. Here, we show for the first time that a glycan of neutral charge, in this case the carbohydrate portion of the Forssman antigen, acts as a ligand for a polyomavirus capsid protein and may thus contribute to host tropism and infective cell entry. These results represent a significant addition to knowledge on polyomavirus-glycan interactions and complement general principles of carbohydrate engagement by viruses. Furthermore, as a specific binding protein of Forssman antigen, VP1 may help to determine levels of this antigen in healthy and malignant tissues in humans.

biochemistry↗

bioRxiv2023

Pathogen and human NDPK-proteins promote AML cell survival via monocyte NLRP3-inflammasome activation.

A history of infection has been linked with increased risk of acute myeloid leukaemia (AML) and related myelodysplastic syndromes (MDS). Furthermore, AML and MDS patients suffer frequent infections because of disease-related impaired immunity. However, the role of infections in the development and progression of AML and MDS remains poorly understood. We and others previously demonstrated that the human nucleoside diphosphate kinase (NDPK) NM23-H1 protein promotes AML blast cell survival by inducing secretion of IL-1{beta} from accessory cells. NDPKs are an evolutionary highly conserved protein family and pathogenic bacteria secrete NDPKs that regulate virulence and host-pathogen interactions. Here, we demonstrate the presence of IgM antibodies against a broad range of pathogen NDPKs and more selective IgG antibody activity against pathogen NDPKs in the blood of AML patients and normal donors, demonstrating that in vivo exposure to NDPKs likely occurs. We also show that pathogen derived NDPK-proteins faithfully mimic the catalytically independent pro-survival activity of NM23-H1 against primary AML cells. Flow cytometry identified that pathogen and human NDPKs selectively bind to monocytes in peripheral blood. We therefore used vitamin D3 differentiated monocytes from wild type and genetically modified THP1 cells as a model to demonstrate that NDPK-mediated IL-1{beta} secretion by monocytes is NLRP3-inflammasome and caspase 1 dependent, but independent of TLR4 signaling. Monocyte stimulation by NDPKs also resulted in activation of NF-{kappa}B and IRF pathways but did not include the formation of pyroptosomes or result in pyroptotic cell death which are pivotal features of canonical NLRP3 inflammasome activation. In the context of the growing importance of the NLRP3 inflammasome and IL-1{beta} in AML and MDS, our findings now implicate pathogen NDPKs in the pathogenesis of these diseases. Author SummaryAcute myeloid leukaemia (AML) and myelodysplastic syndromes MDS) are related blood cancers that are associated with frequent infections because the cancers suppress normal immunity. These infections are therefore generally considered as medical complications arising as a result of but separate to the cancer. However, we provide evidence here that infections may promote or drive cancer progression. We and others previously demonstrated that a human protein called NM23-H1 promotes the survival of AML cells by eliciting survival signals from other cells. NM23-H1 belongs to a highly conserved family of proteins that also occur in bacteria and fungi that cause infections in AML and MDS patients. Here we demonstrate that these bacterial and fungal proteins recapitulate the pro-survival effect of NM23-H1 on AML cells. We also determine that these effects are mediated via mechanisms already known to be important in the development and progression of AML and MDS. This study is the first to identify NM23-H1 like proteins from pathogenic microorganisms as novel activators of these pathways. These findings have important implications for how we understand infections in AML and MDS patients and suggest that in addition to being the consequence of these diseases, infections may also drive the cancer process.

microbiology↗

bioRxiv2022

Structural and functional analysis of natural capsid variants reveals sialic-acid independent entry of BK polyomavirus

BK Polyomavirus (BKPyV) is an opportunistic pathogen that causes nephropathy in kidney transplant recipients. The BKPyV major capsid protein, VP1, engages gangliosides, lipid-linked sialylated glycans at the cell surface, to gain entry into cells. Here, we characterise the influence of VP1 mutations observed in patients with persistent post-transplant BKPyV replication on ganglioside binding, VP1 protein structure, and the tropism of the virus in two renal cell lines: 293TT and immortalised renal tubular epithelial (RS) cells. Infectious entry of single mutants E73Q, E73A and the triple mutant A72V-E73Q-E82Q (VQQ) remained sialic acid-dependent. These three variants acquired binding to a-series gangliosides, including GD1a, although only E73Q was able to infect GD1a-supplemented LNCaP or GM95 cells. Crystal structures of the three mutants showed a clear shift of the BC2 loop in mutants E73A and VQQ that correlated with the inability of these VP1 variants to infect ganglioside complemented cells. On the other hand, the double mutant K69N-E82Q lost the ability to bind sialic acid, with the K69N mutation leading to a steric clash which precludes sialic acid binding. Nevertheless, this mutant retained significant infectivity in 293TT cells that was not dependent on heparan sulphate proteoglycans, implying that an unknown sialic acid-independent entry receptor for BKPyV exists.

microbiology↗

bioRxiv2021

Mycobacterium abscessus biofilms produce an ECM and have a distinct mycolic acid profile

A non-tuberculous mycobacterium (NTM), Mycobacterium abscessus is an emerging opportunistic pathogen associated with difficult to treat pulmonary infections, particularly in patients suffering from cystic fibrosis. It is capable of forming biofilms in vitro that result in an increase of already high levels of antibiotic resistance in this bacterium. Evidence that M. abscessus forms biofilm-like microcolonies in patient lungs and on medical devices further implicated the need to investigate this biofilm in detail. Therefore, in this study we characterized the M. abscessus pellicular biofilm, formed on a liquid-air interface, by studying its molecular composition, and its transcriptional profile in comparison to planktonic cells. Using scanning electron micrographs and fluorescence microscopy, we showed that M. abscessus biofilms produce an extracellular matrix composed of lipids, proteins, carbohydrates and eDNA. Transcriptomic analysis of biofilms revealed an upregulation of pathways involved in the glyoxylate shunt, redox metabolism and mycolic acid biosynthesis. Genes involved in elongation and desaturation of mycolic acids were highly upregulated in biofilms and, mirroring those findings, biochemical analysis of mycolates revealed molecular changes and an increase in mycolic acid chain length. Together these results give us an insight into the complex structure of M. abscessus biofilms, the understanding of which may be adapted for clinical use in treatment of biofilm infections, including strategies for dispersing the ECM, allowing antibiotics to gain access to bacteria within the biofilm.

microbiology↗

bioRxiv2019

Tetraspanin Tspan15 is an essential subunit of an ADAM10 scissor complex

A disintegrin and metalloprotease 10 (ADAM10) is essential for embryonic development and impacts on diseases such as cancer, Alzheimers and inflammatory diseases. ADAM10 is a molecular scissor that proteolytically cleaves the extracellular region from over 100 substrates, including Notch, amyloid precursor protein, cadherins, growth factors and chemokines. ADAM10 was recently proposed to function as six distinct scissors with different substrates, depending on its association with one of six regulatory tetraspanins, termed TspanC8s. However, it remains unclear to what degree ADAM10 function is critically dependent on a TspanC8 partner. To address this, we generated the first monoclonal antibodies to Tspan15 as a model TspanC8. These were used to show that ADAM10 is the principal Tspan15-interacting protein, that Tspan15 expression requires ADAM10 in cell lines and primary cells, and that a synthetic ADAM10/Tspan15 fusion protein is a functional scissor. Together these findings suggest that ADAM10 exists as an intimate ADAM10/TspanC8 scissor complex.

cell biology↗