Synthetic construct of the common ancestor of haloalkane dehalogenases and Renilla luciferase with fragment transplabntation (Anc-FT) AncFT
Comment
Luciferase from Renilla reniformis (RLuc) catalyzes the degradation of coelenterazine in the presence of molecular oxygen, resulting in the product coelenteramide, carbon dioxide, and the desired photon of light (EC 1.13.12.5). This enzyme belongs to the Haloalkane dehalogenase family II with a different catalytic function (EC 3.8.1.5) Reconstruction of the ancestral enzyme shows it has both hydrolase and monooxygenase activities ( Chaloupkova et al.) Preprint available of: Engineering Protein Dynamics of Ancestral Luciferase DOI: 10.26434/chemrxiv.12808295
(Below N is a link to NCBI taxonomic web page and E link to ESTHER at designed phylum.) > other sequences: NE > artificial sequences: NE > synthetic construct: NE
LegendThis sequence has been compared to family alignement (MSA) red => minority aminoacid blue => majority aminoacid color intensity => conservation rate title => sequence position(MSA position)aminoacid rate Catalytic site Catalytic site in the MSA ATGDEWWAKCKQVDVLDSEMSYYDSDPGKHKNTVIFLHGNPTSSYLWRNV IPHVEPLARCLAPDLIGMGKSGKLPNHSYRFVDHYRYLSAWFDSVNLPEK VTIVCHDWGSGLGFHWCNEHRDRVKGIVHMESVVDVIESWDEWPDIEEDI ALIKSEAGEEMVLKKNFFIERLLPSSIMRKLSEEEMDAYREPFVEPGESR RPTLTWPREIPIKGDGPEDVIEIVKSYNKWLSTSKDIPKLFINADPGFFS NAIKKVTKNWPNQKTVTVKGLHFLQEDSPEEIGEAIADFLNELT
The widely used coelenterazine-powered Renilla luciferase was discovered over 40 years ago, but the oxidative mechanism by which it generates blue photons remains unclear. Here we decipher Renilla-type catalysis through crystallographic, spectroscopic and computational experiments. Structures of ancestral and extant luciferases complexed with the substrate-like analogue azacoelenterazine or a reaction product were obtained, providing molecular snapshots of coelenterazine-to-coelenteramide oxidation. Bound coelenterazine adopts a Y-shaped conformation, enabling the deprotonated imidazopyrazinone component to attack O2 via a radical charge-transfer mechanism. A high emission intensity is secured by an aspartate from a conserved proton-relay system, which protonates the excited coelenteramide product. Another aspartate on the rim of the catalytic pocket fine-tunes the electronic state of coelenteramide and promotes the formation of the blue light-emitting phenolate anion. The results obtained also reveal structural features distinguishing flash-type from glow-type bioluminescence, providing insights that will guide the engineering of next-generation luciferase-luciferin pairs for ultrasensitive optical bioassays.
The widely used coelenterazine-powered Renilla luciferase was discovered over 40 years ago but the oxidative mechanism by which it generates blue photons remains unclear. Here we decipher Renilla-type bioluminescence through crystallographic, spectroscopic, and computational experiments. Structures of ancestral and extant luciferases complexed with the substrate-like analogue azacoelenterazine or a reaction product were obtained, providing unprecedented snapshots of coelenterazine-to-coelenteramide oxidation. Bound coelenterazine adopts a Y-shaped conformation, enabling the deprotonated imidazopyrazinone component to attack O2 via a radical charge-transfer mechanism. A high emission intensity is secured by an aspartate from a conserved proton-relay system, which protonates the excited coelenteramide product. Another aspartate on the rim of the catalytic pocket fine-tunes the electronic state of coelenteramide and promotes the formation of the blue light-emitting phenolate anion. The results obtained also reveal structural features distinguishing flash-type from glow-type bioluminescence, providing insights that will guide the engineering of next-generation luciferase-luciferin pairs for ultrasensitive optical bioassays.
To obtain structural insights into the emergence of biological functions from catalytically promiscuous enzymes, we reconstructed an ancestor of catalytically distinct, but evolutionarily related, haloalkane dehalogenases (EC 3.8.1.5) and Renilla luciferase (EC 1.13.12.5). This ancestor has both hydrolase and monooxygenase activities. Its crystal structure solved to 1.39 A resolution revealed the presence of a catalytic pentad conserved in both dehalogenase and luciferase descendants and a molecular oxygen bound in between two residues typically stabilizing a halogen anion. The differences in the conformational dynamics of the specificity-determining cap domains between the ancestral and descendant enzymes were accessed by molecular dynamics and hydrogen-deuterium exchange mass spectrometry. Stopped-flow analysis revealed that the alkyl enzyme intermediate formed in the luciferase-catalyzed reaction is trapped by blockage of a hydrolytic reaction step. A single-point mutation (Ala54Pro) adjacent to one of the catalytic residues bestowed hydrolase activity on the modern luciferase by enabling cleavage of this intermediate. Thus, a single substitution next to the catalytic pentad may enable the emergence of promiscuous activity at the enzyme class level, and ancestral reconstruction has a clear potential for obtaining multifunctional catalysts.
Synthetic construct of the common ancestor of haloalkane dehalogenases and Renilla luciferase with fragment transplabntation (Anc-FT) AncFT
