Biology subjects

Nowick, J. S.

Publications and source records attributed to Nowick, J. S..

4 recordsLinked to original sources

bioRxiv2025

Antibodies raised against a structurally defined Aβ oligomer mimic protect human iPSC neurons from Aβ toxicity at sub-stoichiometric concentrations

Anti-A{beta} antibodies are important tools for identifying structural features of aggregates of the A{beta} peptide and are used in many aspects of Alzheimers disease (AD) research. Our laboratory recently reported the generation of a polyclonal antibody, pAb2AT-L, that is moderately selective for oligomeric A{beta} over monomeric and fibrillar A{beta} and recognizes the diffuse peripheries of A{beta} plaques in AD brain tissue but does not recognize the dense fibrillar plaque cores. This antibody was generated against 2AT-L, a structurally defined A{beta} oligomer mimic composed of three A{beta}-derived {beta}-hairpins arranged in a triangular fashion and covalently stabilized with three disulfide bonds. In the current study, we set out to determine if pAb2AT-L is neuroprotective against toxic aggregates of A{beta} and found that pAb2AT-L protects human iPSC-derived neurons from A{beta}42-mediated toxicity at molar ratios as low as 1:100 antibody to A{beta}42, with a ratio of 1:25 almost completely rescuing cell viability. Few other antibodies have been reported to exhibit neuroprotective effects at such low ratios of antibody to A{beta}. ThT and TEM studies indicate that pAb2AT-L delays but does not completely inhibit A{beta}42 fibrillization at sub-stoichiometric ratios. The ability of pAb2AT-L to inhibit A{beta}42 toxicity and aggregation at sub-stoichiometric ratios suggests that pAb2AT-L binds toxic A{beta}42 oligomers and does not simply sequester monomeric A{beta}42. These results further suggest that toxic oligomers of A{beta}42 share significant structural similarities with 2AT-L. TOC Graphic O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=108 SRC="FIGDIR/small/654602v1_ufig1.gif" ALT="Figure 1"> View larger version (16K): org.highwire.dtl.DTLVardef@d97c84org.highwire.dtl.DTLVardef@7dd416org.highwire.dtl.DTLVardef@ef072borg.highwire.dtl.DTLVardef@bfd614_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2023

Supramolecular Interactions of Teixobactin Analogues in the Crystal State

Teixobactin is a potent peptide antibiotic against Gram-positive bacteria that binds to lipid II and related peptidoglycan precursors and disrupts the cell membrane. This paper presents the X-ray crystallographic structure of the N-methylated teixobactin analogue N-Me-D-Gln4,Lys10-teixobactin (1). N-Methylation at position 4 prevents uncontrolled aggregation and enables the crystallization of the teixobactin analogue. Lysine at position 10 replaces the non-proteinogenic amino acid allo-enduracididine, which is not commercially available. Crystallization from aqueous solution with MgCl2 and PEG3350 afforded crystals suitable for X-ray crystallography. The crystallographic phases were solved using SAD phasing on data sets collected at 2.0663 [A]. Molecular replacement then enabled the determination of the structure at 1.50 [A] resolution using a data set collected at 0.9997[A] (PDB 8U78). Eight peptide molecules comprise the asymmetric unit, with each peptide molecule binding a chloride anion through hydrogen bonding with the amide NH group of residues 7, 8, 10, and 11. The peptide molecules form hydrogen-bonded antiparallel {beta}-sheet dimers in the crystal lattice, with residues 1-3 comprising the dimerization interface. The dimers further assemble end-to-end in the crystal lattice. The {beta}-sheet dimers are amphiphilic, with the side chains of the hydrophobic residues on one surface and the side chains of the hydrophilic residues on the other surface. The dimers pack in the lattice through hydrophobic interactions between the hydrophobic surfaces. The crystal structure of teixobactin analogue 1 recapitulates several aspects of the interaction of teixobactin with the cell membrane of Grampositive bacteria, including anion binding, supramolecular assembly through {beta}-sheet formation, and hydrophobic interactions.

microbiology↗

bioRxiv2023

Antibodies Raised Against an Aβ Oligomer Mimic Recognize Pathological Features in Alzheimer's Disease and Associated Amyloid-Disease Brain Tissue

Antibodies that target the {beta}-amyloid peptide (A{beta}) and its associated assemblies are important tools in Alzheimers disease research and have emerged as promising Alzheimers disease therapies. This paper reports the creation and characterization of a triangular A{beta} trimer mimic composed of A{beta}l7-36 {beta}-hairpins, and the generation and study of polyclonal antibodies raised against the A{beta} trimer mimic. The A{beta} trimer mimic is covalently stabilized by three disulfide bonds at the corners of the triangular trimer to create a homogeneous oligomer. Structural, biophysical, and cell-based studies demonstrate that the A{beta} trimer mimic shares characteristics with oligomers of full-length A{beta}: X-ray crystallography elucidates the high-resolution structure of the trimer and reveals that four copies of the trimer assemble to form a dodecamer; SDS-PAGE, size exclusion chromatography, and dynamic light scattering reveal that the trimer also forms higher-order assemblies in solution; cell-based toxicity assays show that the trimer elicits LDH release, decreases ATP levels, and activates caspase-3/7 mediated apoptosis. Tmmunostaining studies on brain slices from people who lived with Alzheimers disease as well as people who lived with Down syndrome reveal that the polyclonal antibodies raised against the A{beta} trimer mimic recognize pathological features including different types of A{beta} plaques and cerebral amyloid angiopathy. These findings suggest that the triangular trimer structural motif is important in Alzheimers disease and may thus constitute a new structurally defined molecular target for diagnostic and therapy development. SYNOPSISA structurally defined A{beta} oligomer mimic is created and studied, and antibodies raised against the A{beta} oligomer mimic are used to investigate its relevance to Alzheimers disease.

neuroscience↗

bioRxiv2020

Structure-Based Design of a Cyclic Peptide Inhibitor of the SARS-CoV-2 Main Protease

This paper presents the design and study of a first-in-class cyclic peptide inhibitor against the SARS-CoV-2 main protease (Mpro). The cyclic peptide inhibitor is designed to mimic the conformation of a substrate at a C-terminal autolytic cleavage site of Mpro. Synthesis and evaluation of a first-generation cyclic peptide inhibitor reveals that the inhibitor is active against Mpro in vitro and is non-toxic toward human cells in culture. The initial hit described in this manuscript, UCI-1, lays the groundwork for the development of additional cyclic peptide inhibitors against Mpro with improved activities.

biochemistry↗