Biology subjects

Devitt, G.

Publications and source records attributed to Devitt, G..

4 recordsLinked to original sources

bioRxiv2024

Aggregation promoting sequences rather than phosphorylation are essential for Tau-mediated toxicity in Drosophila

BackgroundDisease-modifying therapies for tauopathies like Alzheimers disease have targeted Tau hyperphosphorylation and aggregation, as both pathological manifestations are implicated in Tau-mediated toxicity. However, the relative contributions of these pathology-linked changes to Tau neurotoxicity remain unclear. MethodsLeveraging the genetic tractability of Drosophila, we generated multiple inducible human Tau transgenes with altered phosphorylation status and/or aggregation propensity. Their individual and combined impact was tested in vivo by quantifying Tau accumulation and neurodegenerative phenotypes in the aging fly nervous system. ResultsWe report that phospho-mimicking Tau (hTau2N4RE14) induced profound neurodegeneration, supporting a neurotoxic role for phosphorylation. However, when we rendered hTau2N4RE14 aggregation incompetent, by deleting the 306VQIVYK311 motif in the microtubule-binding region, neurotoxicity was abolished. Moreover, a peptide inhibitor targeting this motif efficaciously reduced Tau toxicity in aging Drosophila. ConclusionNeurodegeneration mediated by Tau hyperphosphorylation is gated via at least one aggregation-mediating motif on the protein. This highlights the primacy of blocking Tau aggregation in therapy, perhaps without the need to clear phosphorylated species.

neuroscience↗

bioRxiv2023

Growth inhibitory factor/metallothionein-3 is a sulfane sulfur-binding protein

Cysteine-bound sulfane sulfur atoms in proteins have received much attention as key factors in cellular redox homeostasis. However, the role of sulfane sulfur in zinc regulation has been underinvestigated. We report here that cysteine-bound sulfane sulfur atoms serve as ligands to hold and release zinc ions in growth inhibitory factor (GIF)/metallothionein-3 (MT-3) with an unexpected C-S-S-Zn structure. Oxidation of such a zinc/persulfide cluster in Zn7GIF/MT-3 results in the release of zinc ions, and intramolecular tetrasulfide bridges in apo-GIF/MT-3 efficiently undergo S-S bond cleavage by thioredoxin to regenerate Zn7GIF/MT-3. Three-dimensional molecular modeling confirmed the critical role of the persulfide group in the thermostability and Zn-binding affinity of GIF/MT-3. The present discovery raises the fascinating possibility that the function of other Zn-binding proteins is controlled by sulfane sulfur.

biochemistry↗

bioRxiv2023

Mechanisms of SARS-CoV-2 Inactivation using UVC Laser Radiation

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) has had a tremendous impact on humanity. Prevention of transmission by disinfection of surfaces and aerosols through a chemical-free method is highly desirable. Ultraviolet C (UVC) light is uniquely positioned to achieve inactivation of pathogens. We report the inactivation of SARS-CoV-2 virus by UVC radiation and explore its mechanisms. A dose of 50mJ/cm2 using a UVC laser at 266nm achieved an inactivation efficiency of 99.89%, whilst infectious virions were undetectable at 75mJ/cm2 indicating >99.99% inactivation. Infection by SARS-CoV-2 involves viral entry mediated by the spike glycoprotein (S), and viral reproduction, reliant on translation of its genome. We demonstrate that UVC radiation damages ribonucleic acid (RNA) and provide in-depth characterisation of UVC-induced damage of the S protein. We find that UVC severely impacts SARS-CoV-2 spike proteins ability to bind human angiotensin-converting enzyme 2 (hACE2) and this correlates with loss of native protein conformation and aromatic amino acid integrity. This report has important implications for the design and development of rapid and effective disinfection systems against the SARS-CoV-2 virus and other pathogens.

microbiology↗

bioRxiv2022

Multi-excitation Raman Spectroscopy Complements Whole Genome Sequencing for Rapid Detection of Bacterial Infection and Resistance in WHO Priority Pathogens

Current methods for diagnosing acute and complex infections mostly rely on culture-based methods and, for biofilms, fluorescence in-situ hybridization. These techniques are labor-intensive and can take 2-4 days to return a test result, especially considering an extra culturing step required for the antibiotic susceptibility testing (AST). This places a significant burden on healthcare providers, delaying treatment and leading to adverse patient outcomes. Here, we report the complementary use of our newly developed multi-excitation Raman spectroscopy (ME-RS) method with whole-genome sequencing (WGS). Four WHO priority pathogens are AST phenotyped and their antimicrobial resistance (AMR) profile determined by WGS. On application of ME-RS method we find high correlation with the WGS characterization. Highly accurate classification based on the species (98.93%), wild-type/non-wild type (99.45%), and presence or absence of thick peptidoglycan layers in cell walls (100%), as well as at the individual strain level (99.29%). These results clearly demonstrate the potential of ME-RS as a rapid and first-stage tool for species, resistance and strain-level classification which can be followed up by WGS for confirmation. Such a workflow can facilitate efficient antimicrobial stewardship to handle and prevent the spread of AMR.

microbiology↗