Confirmation of color determination factors for Ser286 derivatives of firefly luciferase from Luciola cruciata (LUC-G)

The bioluminescence color of firefly luciferase including its mutants ranges from green to red (530–640 nm) and is affected by the species of firefly, the reaction conditions, and by the substitution of amino acids. Although there is a general agreement that the microenvironment mechanism is the dominant model for the color determination of firefly luciferase, a complete mechanism has not been shown, partially due to the lack of comprehensive data on which amino acid positions alter the bioluminescent color. In this paper, a mutant library of position serine 286 (S286) in Luciola cruciata luciferase (LUC-G) was constructed and characterized. The substitution of S286 resulted in a drastic red shift in bioluminescence color (>600 nm), and only glycine (G) and alanine (A) mutants remained yellow-green. To explain this color difference, molecular dynamics (MD) calculations of 3 S286 derivatives (S286G, S286N, and S286I), in addition to wild type (WT), were performed. The active site rigidity and active site hydrogen bonding networks were compared to WT for each derivative. The results suggested that both factors affected the active site environment and affected the difference in bioluminescence colors in LUC-G S286 derivatives.

Graphical abstractWe constructed a mutant library of Japanese firefly Luciola cruciata luciferase (LUC-G) at position S286 and performed conclusive characterization of these mutants to determine their bioluminescence properties. We also proposed a model for bioluminescence color changes using predicted structures of the luciferase mutants and studied active site rigidity and the hydrogen bonding network.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The bioluminescence color of almost S286 mutants of firefly luciferase, LUC-G, changed to red. ► Conclusive characterization of bioluminescence properties and MD simulations were performed. ► Active site rigidity and hydrogen bonding network were both important for the color determination of S286 derivatives.