Biology subjects

Keeble, A. H.

Publications and source records attributed to Keeble, A. H..

4 recordsLinked to original sources

bioRxiv2026

LemonCatcher Acidic Pull-Down Enables Selective In-Cell Hydrogen-Deuterium Exchange Mass Spectrometry

Proteins are dynamic molecules which sensitively adapt according to their environment. Hydrogen-Deuterium eXchange Mass Spectrometry (HDX-MS) provides unique insights into protein conformational processes. However, existing methodology cannot selectively enrich proteins post-labeling because D-to-H back exchange must be minimized by rapid processing at pH 2.3-3.0 and 0 {degrees}C, where affinity purification fails. Here, we create LemonCatcher, a protein superglue that spontaneously forms an amide bond to the LemonTag peptide under these harsh acidic and cold quench conditions, even at -20 {degrees}C. Engineering of a bead-coupled LemonCatcher purification system introduces fast and selective quench-capture HDX-MS (SelQueX) on LemonTagged fusion proteins. We demonstrate targeted measurement of protein dynamics in living bacterial cells, revealing ligand-induced conformational changes in maltose-binding protein. Moreover, probing a stalled membrane protein nascent-chain supports a role for the ribosome in maintaining partially unfolded folding intermediates. Thus, SelQueX makes possible selective characterization of protein structural dynamics within the complex cellular milieu.

biochemistry↗

bioRxiv2025

The SpyBLI cell-free pipeline for the rapid quantification of binding kinetics from crude samples

Accurate measurements of binding kinetics, encompassing equilibrium dissociation constant (KD), association rate (kon), and dissociation rate (ko,), are critical for the development and optimisation of high-affinity binding proteins. However, such measurements require highly purified material and precise ligand immobilisation, limiting the number of binders that can be characterised within a reasonable timescale and budget. Here, we present the SpyBLI method, a rapid and cost-effective biolayer interferometry (BLI) pipeline that leverages the SpyCatcher003-SpyTag003 covalent association, eliminating the need for both binder purification and concentration determination. This approach allows for accurate binding-kinetic measurements to be performed directly from crude mammalian-cell supernatants or cell-free expression mixtures. We also introduce a linear gene fragment design that enables reliable expression in cell-free systems without any PCR or cloning steps, allowing binding kinetics data to be collected in under 24 hours from receiving inexpensive DNA fragments, with minimal hands-on time. We demonstrate the methods broad applicability using a range of nanobodies and single-chain antibody variable fragments (scFvs), with affinity values spanning six orders of magnitude. By minimising sample preparation and employing highly controlled, ordered sensor immobilisation, our workflow delivers reliable kinetic measurements from crude mixtures without sacrificing precision. We expect that the opportunity to carry out rapid and accurate binding measurements in good throughput should prove especially valuable for binder engineering, the screening of next-generation sequencing-derived libraries, and computational protein design, where large numbers of potential binders for the same target must be rapidly and accurately characterised to enable iterative refinement and candidate selection.

biophysics↗

bioRxiv2023

SpyCombinator Assembly of Bispecific Binders

Bispecific antibodies are a successful and expanding therapeutic class, bridging two cell-types or engaging two different molecules on the same cell. Bispecifics unlock avenues towards synergy, resistance evasion, and signaling bias. Standard approaches to generate bispecifics are complicated by the need for disulfide reduction/oxidation or cloning of each binder molecule in two different formats. Here we present a modular approach to bispecifics using SpyTag/SpyCatcher spontaneous amidation, where all binders are cloned in the same format, bearing a SpyTag. Two SpyTag-fused antigen-binding modules can be precisely conjugated onto DoubleCatcher, a tandem SpyCatcher where the second Catcher is unreactive until unveiling of reactivity using site-specific protease. Assembly on DoubleCatcher is efficient in phosphate-buffered saline at 37 {degrees}C, with half-times less than 5 min for both SpyCatcher arms and over 97% bispecific homogeneity. We engineer a panel of DoubleCatchers, locked through disulfide bonds to direct binders to project in different directions from the hub. We establish a generalized methodology for one-pot assembly and purification of bispecifics in 96-well plate format. A panel of Fab, affibody or nanobody binders recognizing different sites on HER2 were coupled to DoubleCatcher, revealing unexpected combinations with anti-proliferative or pro-proliferative activity on HER2-addicted cancer cells. Bispecific activity depended sensitively on both the order of the binders within the assembly and the geometry of DoubleCatcher scaffolds. These findings support the need for straightforward assembly in different formats. SpyMask provides a simple and scalable tool to discover synergy in bispecific activity, through modulating receptor organization and geometry.

bioengineering↗

bioRxiv2023

Multiviral Quartet Nanocages Elicit Broad Anti-Coronavirus Responses for Proactive Vaccinology

Defending against future pandemics may require vaccine platforms that protect across a range of related pathogens. The presentation of multiple receptor-binding domains (RBDs) from evolutionarily-related viruses on a nanoparticle scaffold elicits a strong antibody response to conserved regions. Here we produce quartets of tandemly-linked RBDs from SARS-like betacoronaviruses coupled to the mi3 nanocage through a SpyTag/SpyCatcher spontaneous reaction. These Quartet Nanocages induce a high level of neutralizing antibodies against several different coronaviruses, including against viruses not represented on the vaccine. In animals primed with SARS-CoV-2 Spike, boost immunizations with Quartet Nanocages increased the strength and breadth of an otherwise narrow immune response. Quartet Nanocages are a strategy with potential to confer heterotypic protection against emergent zoonotic coronavirus pathogens and facilitate proactive pandemic protection. One Sentence SummaryA vaccine candidate with polyprotein antigens displayed on nanocages induces neutralizing antibodies to multiple SARS-like coronaviruses.

immunology↗