Biology subjects

Fuller, J. R.

Publications and source records attributed to Fuller, J. R..

5 recordsLinked to original sources

bioRxiv2025

A Dual-Action Mechanism to Prevent OX40 Signaling: The Structural Basis for the Differentiated Antagonist STAR-0310

Atopic dermatitis (AD) is a chronic inflammatory disease sustained by dysregulated T cell activity. The OX40/OX40L pathway drives effector and memory T cell proliferation, survival, and cytokine production, making it a key therapeutic target. STAR-0310, a novel anti-OX40 antibody, binds a noncanonical epitope that sterically blocks receptor trimerization without inducing agonism. Structural and functional studies demonstrated a dual mechanism: prevention of new OX40/OX40L interactions and efficient disruption of pre-formed complexes, outperforming comparator antibodies. The pure antagonism and complex disruption capacity of STAR-0310 support its clinical evaluation (NCT06782477) as a differentiated OX40-targeted therapy for AD. HighlightsO_LINovel binding mechanism: STAR-0310 engages OX40 distal to the OX40L site, sterically blocking receptor trimerization without inducing agonism. C_LIO_LIDual action: Prevents formation of new OX40/OX40L complexes and efficiently disrupts pre-formed complexes sustaining inflammation. C_LIO_LIDifferentiation from competitors: Achieves greater efficiency in complex disruption compared with rocatinlimab and IMG-007 with no partial agonist activity. C_LIO_LIClinical potential: Pure antagonist profile supports ongoing evaluation of STAR-0310 (NCT06782477) as a best-in-class OX40 therapy for atopic dermatitis. C_LI

pharmacology and toxicology↗

bioRxiv2025

Structural basis of directionality control in large serine integrases

Large serine integrases (LSIs) catalyze unidirectional site-specific insertion of large DNA payloads, and in the presence of a cognate recombination directionality factor (RDF), catalyze unidirectional excision. Because neither reaction changes the net number of covalent bonds, the preferred direction must be controlled by the energetics of the changing protein-DNA complexes along these reaction pathways. However, a detailed understanding has been hampered by a lack of structural information. Here, we report 8 structures of SP{beta} integrase-DNA complexes along the integrative (-RDF) and excisive (+RDF) reaction pathways, at resolutions extending to 3.15 [A]. These complexes include tetrameric intermediates before and after strand exchange and product-bound dimers for both pathways. Our findings reveal that both recombination-induced conformational changes and RDF-mediated repositioning of the integrases coiled-coil subdomain (1) dictate which pairs of DNA sites can be assembled into a synaptic complex to initiate recombination and (2) dictate which product complexes will be conformationally locked, preventing back reactions. Critically, we find that the synaptic complex in which excision occurs is fundamentally different from that in which integration occurs. These mechanistic insights provide a conceptual framework for engineering efficient and versatile genome editing tools.

biochemistry↗

bioRxiv2023

Cryo-EM structures of PP2A:B55-FAM122A and PP2A:B55-ARPP19

Progression through the cell cycle is controlled by regulated and abrupt changes in phosphorylation.1 Mitotic entry is initiated by increased phosphorylation of mitotic proteins, a process driven by kinases,2 while mitotic exit is achieved by counteracting dephosphorylation, a process driven by phosphatases, especially PP2A:B55.3 While the role of kinases in mitotic entry is well-established, recent data have shown that mitosis is only successfully initiated when the counterbalancing phosphatases are also inhibited.4 For PP2A:B55, inhibition is achieved by the two intrinsically disordered proteins (IDPs), ARPP19 (phosphorylation-dependent)6,7 and FAM122A5 (inhibition is phosphorylation-independent). Despite their critical roles in mitosis, the mechanisms by which they achieve PP2A:B55 inhibition is unknown. Here, we report the cryo-electron microscopy structures of PP2A:B55 bound to phosphorylated ARPP19 and FAM122A. Consistent with our complementary NMR spectroscopy studies both IDPs bind PP2A:B55, but do so in highly distinct manners, unexpectedly leveraging multiple distinct binding sites on B55. Our extensive structural, biophysical and biochemical data explain how substrates and inhibitors are recruited to PP2A:B55 and provides a molecular roadmap for the development of therapeutic interventions for PP2A:B55 related diseases.

biochemistry↗

bioRxiv2022

A bivalent EBV vaccine induces neutralizing antibodies that block B and epithelial cell infection and confer immunity in humanized mice

Epstein Barr virus (EBV) is the major cause of infectious mononucleosis and is associated with several human cancers. Despite its prevalence and major impact on human health, there are currently no specific vaccines or treatments. Four viral glycoproteins, gp 350 and gH/gL/gp42 mediate entry into the major sites of viral replication, B cells and epithelial cells. Here, we designed a nanoparticle vaccine displaying these proteins and show that it elicits potent neutralizing antibodies that protect against infection in vivo. Based on structural analyses, we designed single chain gH/gL and gH/gL/gp42 proteins that were each fused to bacterial ferritin to form a self-assembling nanoparticles. X-ray crystallographic analysis revealed that single chain gH/gL and gH/gL/gp42 adopted a similar conformation to the wild type proteins, and the protein spikes were observed by electron microscopy. Single chain gH/gL or gH/gL/gp42 nanoparticle vaccines were constructed to ensure product homogeneity needed for clinical development. These vaccines elicited neutralizing antibodies in mice, ferrets, and non-human primates that inhibited EBV entry into both B cells and epithelial cells. When mixed with a previously reported gp350 nanoparticle vaccine, gp350D123, no immune competition was observed. To confirm its efficacy in vivo, humanized mice were challenged with EBV after passive transfer of IgG from mice vaccinated with control, gH/gL/gp42+gp350D123 or gH/gL+gp350D123 nanoparticles. While all control animals (6/6) were infected, only one mouse in each vaccine group that received immune IgG had transient low level viremia (1/6). Furthermore, no EBV lymphomas were detected in immune animals in contrast to non-immune controls. This bivalent EBV nanoparticle vaccine represents a promising candidate to prevent EBV infection and EBV-related malignancies in humans. One sentence summaryA bivalent gp350 and gH/gL/gp42 nanoparticle vaccine elicits neutralizing antibodies that protect against EBV infection and EBV lymphoma in vivo.

immunology↗

bioRxiv2021

Structural basis for topological regulation of Tn3 resolvase

Site-specific DNA recombinases play a variety of biological roles, often related to the dissemination of antibiotic resistance, and are also useful synthetic biology tools. The simplest sitespecific recombination systems will recombine any two cognate sites regardless of context. Other systems have evolved elaborate mechanisms, often sensing DNA topology, to ensure that only one of multiple possible recombination products is produced. The closely-related resolvases from the Tn3 and {gamma}{delta} transposons have historically served as paradigms for the regulation of recombinase activity by DNA topology. However, despite many proposals, models of the multi-subunit protein-DNA complex (termed the synaptosome) that enforces this regulation have been unsatisfying due to a lack of experimental constraints and incomplete concordance with experimental data. Here we present new structural and biochemical data that lead to a new, detailed model of the Tn3 synaptosome, and discuss how it harnesses DNA topology to regulate the enzymatic activity of the recombinase.

biochemistry↗