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Hay, S.

Publications and source records attributed to Hay, S..

7 recordsLinked to original sources
bioRxiv2026

Multistate Enzyme Design Enables Efficient and Stereoselective Multistep Catalysis

Enzymes catalyze multistep reactions by stabilizing successive transition states within well organized, yet dynamic active sites. However, computational enzyme design typically targets a single transition state using rigid active-site models. Here, we introduce multistate enzyme design, which uses conformational ensembles to optimize active sites across an entire reaction coordinate. Applied to a de novo Morita--Baylis--Hillmanase, multistate enzyme design outperformed conventional single-state design, with the most active variant achieving >100-fold higher bi-substrate catalytic efficiency and surpassing an extensively optimized enzyme from directed evolution in both efficiency and enantioselectivity. Structural and kinetic analyses revealed that multistate design preserved catalytic preorganization and conformational plasticity, distributed stabilization across the reaction coordinate and avoided kinetic bottlenecks created by single-state optimization. By contrast, single-state design compromised preorganization, destabilized upstream states and shifted rate limitation away from the targeted transition state. Multistate enzyme design provides a framework for designing catalytic landscapes rather than static active sites, opening a route to efficient de novo enzymes for complex multistep chemistry.

biochemistry↗
bioRxiv2025

Identification of Diverse Cellulose Binding Domains using in silico Prioritisation and High-Throughput Screening

In silico pre-screening methods are becoming an increasingly important step in making large scale enzyme screening experiments manageable, particularly in the sampling large protein sequence datasets for maximum diversity. Here, we develop a bioinformatics workflow that utilises automated gene sequence annotation, substrate prediction and structure prediction tools to effectively isolate representative protein sequences, thereby maximising the information gathered on the wider dataset from relatively few in vitro experiments. Included in this workflow is a new tool, ColabAlign, which performs pairwise structural alignments to construct a structure-informed dendrogram, from which representatives are selected based on clustering. The workflow was applied to the identification of cellulose-binding carbohydrate-binding modules (CBMs) suitable for enzyme immobilisation tag development. 47 sequentially and structurally diverse mCherry-CBM fusions were tested for binding against cellulose, chitin and spent coffee grounds (SCG) using a pulldown assay from cell lysate. We successfully identified 5 CBMs with significant binding towards commercial and waste cellulose support materials, suitable for further tag design work. This work also provides the first experimental evidence of chitin binding by one or more members of CBM6 and CBM46.

bioinformatics↗
bioRxiv2025

Integrated structural dynamics uncover new modes of B12 photoreceptor activation

Photoreceptor proteins initiate, regulate and control fundamental biological processes such as vision, photosynthesis and circadian rhythms1. A large photoreceptor subfamily uses vitamin B12 derivatives for light sensing2, contrasting with the well-established mode of action of these organometallic derivatives in thermally activated enzymatic reactions3. The molecular mechanism of B12 photoreception and how this differs to the thermal pathways remain unknown. Here we provide a detailed spatio-temporal description of photoactivation in the prototypical tetrameric B12 photoreceptor CarH4,5 from nanoseconds to seconds by using an integrative approach, combining time- and temperature-resolved structural and spectroscopic methods with quantum chemical calculations. High resolution structural snapshots of key intermediates illustrate how photocleavage of a Co-C bond triggers a pathway of structural changes that propagate throughout CarH from the B12 chromophore, via a previously unknown adduct, to finally cause tetramer dissociation. These unique intermediates, which differentiate CarH from thermally-activated B12 enzymes, steer the photoactivation pathway and act as the molecular bridge between photochemical and photobiological timescales. Our results offer a spatio-temporal understanding of CarH photoactivation and pave the way for designing and optimising B12-dependent photoreceptors for future optogenetic applications.

biophysics↗
bioRxiv2023

Mechanistic implications of the ternary complex structural models for the photoenzyme protochlorophyllide oxidoreductase.

The photoenzyme protochlorophyliide oxidoreductase (POR) is an important enzyme for understanding biological H-transfer mechanisms. It uses light to catalyse the reduction of protochlorophyllide (Pchlide) to chlorophyllide, a key step in chlorophyll biosynthesis. Although a wealth of spectroscopic data have provided crucial mechanistic insight about the light-driven reaction chemistry, a structural rationale for POR photocatalysis has proved more challenging and remains hotly debated. Recent structural models of the ternary enzyme-substrate complex, derived from crystal and electron microscopy data, show differences in the orientation of the Pchlide substrate and the architecture of the POR active site that have significant implications for the catalytic mechanism of Pchlide reduction. Here, we have used a combination of computational and experimental approaches to investigate the compatibility of each of these structural models with the hypothesised reaction mechanisms and propose an alternative structural model for the cyanobacterial POR-Pchlide-NADPH ternary complex based on these findings. Through detailed site-directed mutagenesis studies we show that a strictly conserved Tyr residue, which has previously been proposed to act as the proton donor in POR photocatalysis, is not likely to be involved in this step of the reaction but is crucial for Pchlide binding. Instead, an active site Cys residue is important for both hydride and proton transfer reactions in POR and is proposed to act as the proton donor, either directly or through a water-mediated network. Moreover, a conserved Gln residue is found to be important for Pchlide binding and ensuring efficient photochemistry by tuning its electronic properties, likely by interacting with the central Mg atom of the substrate. This optimal binding pose for the POR ternary enzyme-substrate complex illustrates how light energy can be harnessed to facilitate enzyme catalysis by this unique enzyme.

biochemistry↗
bioRxiv2018

CellHarmony: Cell-level matching and comparison of single-cell transcriptomes

To understand the molecular pathogenesis of human disease, precision analyses to define molecular alterations within (and between) disease-associated cell populations are desperately needed. Single-cell genomics represents an ideal platform to enable the identification and comparison of normal and diseased transcriptional cell states. We note that disease-associated perturbations usually retain cellular-identity programs (core genes), providing an appropriate reference for secondary comparison analyses. Thus, we created cellHarmony, an integrated solution for the unsupervised analysis and classification of cell types from diverse scRNA-Seq datasets. cellHarmony is an automated and easy-to-use tool that efficiently matches single-cell transcriptomes using a community clustering and alignment strategy. Utilizing core genes and community clustering to reveal disease and cell-state systems-level insights overcomes bias toward donor and disease effects that can be imposed by joint-alignment approaches. Moreover, cellHarmony directly compares cell frequencies and gene expression in a cell-type-specific manner, then produces a holistic representation of these differences across potentially dozens of cell populations and impacted regulatory networks. Using this approach, we identify gene regulatory programs that are selectively impacted in distinct hematopoietic and heart cell populations that suggest novel disease mechanisms and drug targets. Thus, this approach holds tremendous promise in revealing the molecular and cellular origins of complex diseases.

bioinformatics↗
bioRxiv2017

Changing geographic patterns and risk factors for avian influenza A(H7N9) infection in China

The 5th epidemic wave in 2016-2017 of avian influenza A(H7N9) virus in China caused more human cases than any previous waves but the factors that may explain the recent range expansion and surge in incidence remain unknown. We investigated the effect of anthropogenic, poultry and wetland information and of market closures on all epidemic waves (1-5). Poultry predictor variables recently became much more important than before, supporting the assumption of much wider H7N9 transmission in the chicken reservoir, that could be linked to increases in pathogenicity. We show that the future range expansion of H7N9 to northern China may translate into a higher risk of coinciding peaks with those of seasonal influenza, leading to a higher risk of reassortments. Live-poultry market closures are showed to be effective in reducing the local incidence rates of H7N9 human cases, but should be paired with other prevention and control measures to prevent transmission.

epidemiology↗