What it is
Designing from scratch an enzyme that cuts amide bonds, the bonds that hold a protein chain together, is a major challenge. The authors use RFdiffusion methods to design proteins whose active site holds a zinc ion that activates a water molecule, placed next to a pocket that binds a peptide substrate. Of 135 designs tested, 36% catalyse cleavage of their cognate peptide substrates at the targeted scissile bond, the bond the enzyme is designed to cut. The best design accelerates peptide-bond hydrolysis by more than 100 million-fold relative to the uncatalysed reaction, and 4 substitutions raise that to more than 10 billion-fold by improving how well the active site is pre-organized. With the same approach the authors design metalloproteases that selectively cleave the human disease-associated proteins TDP-43, amyloid-beta and serum amyloid A, with rate enhancements of up to 1 billion-fold. They further design caged cytokines and receptor antagonists that the designed proteases selectively switch on, giving bioorthogonal control of cell state, control exerted by chemistry that does not interfere with the cell's own. De novo design, they conclude, can yield highly active, programmable proteases with applications in therapeutics, biotechnology and bioremediation.
Why it matters
36% of 135 tested designs cut their target peptide bond, and with 4 substitutions the best ran more than 10 billion-fold faster than the uncatalysed reaction. Cutting an amide bond is one of the harder reactions to design an enzyme for. These proteins hold a zinc ion that activates water beside a pocket that binds the substrate, and the same approach produced proteases that selectively cut the disease-associated proteins TDP-43, amyloid-beta and serum amyloid A, with rate enhancements of up to 1 billion-fold. The authors also built caged cytokines and receptor antagonists that those proteases selectively switch on, giving control over cell state.
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Filed underProtein Structure and Dynamics, Protease and Inhibitor Mechanisms, Enzyme Catalysis and Immobilization