The proton and metal binding sites responsible for the pH-dependent green-red bioluminescence color tuning in firefly luciferases

Autor(es)

Viviani, Vadim R. ^[1] ; Gabriel, Gabriele V. M. ^[2] ; Bevilaqua, Vanessa R. ^[2] ; Simoes, A. F. ^[1] ; Hirano, T. ^[3] ; Lopes-de-Oliveira, P. S. ^[4]

Afiliação do(s) autor(es)

^[1] Fed Univ Sao Carlos UFSCar, Grad Program Biotechnol & Environm Monitoring, Rodovia Joao Leme dos Santos, Km 110, Sorocaba, SP - Brazil

^[2] Fed Univ Sao Carlos UFSCAR, Grad Program Evolut Genet & Mol Biol, Sao Carlos, SP - Brazil

^[3] Tokyo Electrocommun Univ, Tokyo - Japan

^[4] CNPEM, Lab Nacl Biociencias LNBio, Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SCIENTIFIC REPORTS; v. 8, DEC 4 2018.
• Citações Web of Science: 4

Resumo

Firefly luciferases produce yellow-green light under physiological and alkaline conditions, however at acidic pH, higher temperatures or in the presence of heavy metals the color changes to red, a property called pH-sensitivity. Despite many decades of studies, the proton and metal binding sites responsible for pH-sensitivity remain enigmatic. Previously we suggested that the salt bridge E311/R337 keeps a closed conformation of the luciferin phenolate binding site. Here we further investigated the effect of this salt bridge and mutations of the neighbor residues H310 and E/N354, on metal and pH-sensitivity of firefly luciferases emitting distinct bioluminescence colors (Cratomorphus distinctus: 548 nm; Macrolampis sp2: 569 nm). The substitutions of H310 and E/N354 modulate metal sensitivity, whereas the carboxylate of E311 may work as the catalytic base essential for green bioluminescence and pH-sensitivity. Modeling studies showed that H310, E311 and E354 side-chains coordinate Zinc, constituting the metal binding site and the pH-sensor. Electrostatic potential and pKa calculations suggest that the external couple H310/E354 is affected by pH, whereas E311/R337 make a stabilized internal pair which retains excited oxyluciferin ejected proton near its phenolate group into a high energy state, promoting yellow-green bioluminescence. Protonation or metal binding weaken these electrostatic gates and their ability to retain the excited oxyluciferin released proton near its phenolate, promoting red light emission. (AU)

• Processo FAPESP: 10/05426-8 - Bioluminescência de artrópodes: diversidade biológica em biomas brasileiros; origem bioquímica; evolução estrutural/funcional de luciferases; diferenciação molecular das lanternas; aplicações biotecnológicas, ambientais e educacionais
• Beneficiário: Vadim Viviani
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 13/09594-0 - Análise dos transcriptomas das laternas, corpo gorduroso e túbulos de Malpighi de coleópteros, e suas relações com as origens da bioluminescência em Coleoptera e Diptera
• Beneficiário: Vadim Viviani
• Modalidade de apoio: Auxílio à Pesquisa - Regular