Biology subjects

Abramson, J.

Publications and source records attributed to Abramson, J..

6 recordsLinked to original sources

bioRxiv2026

Designing enzymes for new-to-nature chemistry and non-natural substrates with AlphaProtein Novo

Creating highly active enzymes for arbitrary reactions is a transformative goal for the molecular sciences (1). Traditional protein engineering (2,3) is constrained by a reliance on existing natural starting points, which are often challenging to discover. De novo design offers the potential to overcome this by creating enzymes from first principles (4), but has yet to achieve practically relevant catalytic properties. Here we present AlphaProtein Novo (AP Novo), a machine-learning pipeline that demonstrates, for the first time, that de novo enzyme design can outperform natural sequence mining in addressing challenging chemistry. We used AP Novo to design new-to-nature nitrene transferases to synthesise the pharmacophore piperidine with unprecedented product selectivity, and to create enzymes that degrade the environmental toxin DEHP under conditions that denature natural enzymes. We also obtained state-of-the-art catalytic efficiencies on two well-studied model reactions, and through iterative design and analysis found that key enablers of success were mechanism-inspired metrics based on AlphaFold 3 predictions and sequence-ensemble-based scoring of designed backbones. Our results show that de novo design has become a powerful complement to natural enzyme diversity for discovering catalysts for a range of applications.

synthetic biology↗

bioRxiv2026

Design-Evolution Synergy Enables New-to-Nature Enzyme Chemistry

Directed evolution and machine-learning-assisted evolution have transformed biocatalysis by enabling rapid optimisation of catalytic performance within compatible protein scaffolds. In parallel, advances in deep-learning-driven de novo protein design have expanded accessible protein architectural space, enabling the generation of functional catalysts for increasingly challenging transformations. We herein report a synergistic design-evolution strategy to encode new-to-nature regio- and enantioselective C-H amination reactions using engineered de novo haemproteins to synthesise chiral piperidines, a privileged pharmacophore in drug discovery. By integrating motif scaffolding, computational re-design, and directed evolution, we demonstrate de novo enzyme design can enable challenging, high-energy-barrier enzyme chemistry with programmable regio- and enantioselectivity, high catalytic efficiency, excellent enzyme stability, and scaffold diversity.

synthetic biology↗

bioRxiv2023

Biochemical characterization of a GDP-mannose transporter from Chaetomium thermophilum

Nucleotide Sugar Transporters (NSTs) belong to the SLC35 family (human solute carrier) of membrane transport proteins and are crucial components of the glycosylation machinery. NSTs are localized in the ER and Golgi apparatus membranes, where they accumulate nucleotide sugars from the cytosol for subsequent polysaccharide biosynthesis. Loss of NST function impacts the glycosylation of cell surface molecules. Mutations in NSTs cause several developmental disorders, immune disorders, and increased susceptibility to infection. Atomic resolution structures of three NSTs have provided a blueprint for a detailed molecular interpretation of their biochemical properties. In this work, we have identified, cloned, and expressed 18 members of the SLC35 family from various eukaryotic organisms in Saccharomyces cerevisiae. Out of 18 clones, we determined Vrg4 from Chaetomium thermophilum (CtVrg4) is a GDP-mannose transporter with an enhanced melting point temperature (Tm) of 56.9 {degrees}C, which increases with the addition of substrates, GMP and GDP-mannose. In addition, we report--for the first time--that the CtVrg4 shows an affinity to bind to phosphatidylinositol lipids.

biochemistry↗

bioRxiv2022

Epithelial antigen presentation controls commensal-specific intraepithelial T-cells in the gut

The expression of MHCII by intestinal epithelial cells (IEC) determines the severity of intestinal immunopathological reactions. However, the function of MHCII on IEC under homeostatic conditions remains elusive. Here we report that MHCII expression on IECs is a hallmark of an adaptive wave of homeostatic intestinal immune responses to commensal segmented filamentous bacteria (SFB). Focusing on SFB-driven responses, we describe the expression pattern of MHCII and the associated antigen processing machinery among IEC subpopulations along with the cellular network that regulates MHCII induction. Furthermore, we show that SFB induce the accumulation of SFB-specific intraepithelial lymphocytes (IELs) that originate from conventional CD4+ T-cells. Importantly, induced IELs are dependent on the epithelial MHCII. Finally, we demonstrate that both epithelial MHCII and the IEL functionality regulate the epithelial turnover. This study describes the organization of a commensal-targeted, IEL-driven immune response that is controlled by IEC antigen presentation and ultimately regulates IEC turnover.

immunology↗

bioRxiv2022

Reliable energy-based antibody humanization and stabilization

Humanization is an essential step in developing animal-derived antibodies into therapeutics, and approximately one third of approved antibodies have been humanized. Conventional humanization approaches graft the complementarity-determining regions (CDRs) of the animal antibody onto several homologous human frameworks. This process, however, often drastically lowers stability and antigen binding, demanding iterative mutational fine-tuning to recover the original antibody properties. Here, we present Computational hUMan AntiBody design (CUMAb), a web-accessible method that starts from an experimental or model antibody structure, systematically grafts the animal CDRs on thousands of human frameworks, and uses Rosetta atomistic simulations to rank the designs by energy and structural integrity (http://CUMAb.weizmann.ac.il). CUMAb designs of five independent antibodies exhibit similar affinities to the parental animal antibody, and some designs show marked improvement in stability. Surprisingly, nonhomologous frameworks are often preferred to the highest-homology ones, and several CUMAb designs that use different human frameworks and differ by dozens of mutations are functionally equivalent. Thus, CUMAb presents a general and streamlined approach to optimizing antibody stability and expressibility while increasing humanness.

bioengineering↗

bioRxiv2020

MicroED structure of lipid-embedded mammalian mitochondrial voltage dependent anion channel

A near-atomic resolution structure of the mouse voltage dependent anion channel (mVDAC) is determined by combining cryogenic focused ion-beam (FIB) milling and microcrystal electron diffraction (MicroED). The crystals were grown in a viscous modified bicelle suspension which limited their size and made them unsuitable for conventional X-ray crystallography. Individual thin, plate-like crystals were identified using scanning electron microscopy (SEM) and focused ion-beam (FIB) imaging at high magnification. Three crystals were milled into thin lamellae. MicroED data were collected from each lamellae and merged to increase completeness. Unmodelled densities were observed between protein monomers, suggesting the presence of lipids that likely mediate crystal contacts. This work demonstrates the utility of milling membrane protein microcrystals grown in viscous media using a focused ion-beam for subsequent structure determination by MicroED for samples that are not otherwise tractable by other crystallographic methods. To our knowledge, the structure presented here is the first of a membrane protein crystallized in a lipid matrix and solved by MicroED.

biophysics↗