Recombinant light-sensitive photoprotein berovin from ctenophore Beroe abyssicola: Bioluminescence and absorbance characteristics

The bright bioluminescence of ctenophores inhabiting the oceans worldwide is caused by light-sensitive Ca2thorn -regulated photoproteins. By now, the cDNAs encoding photoproteins from the four different ctenophore species have been cloned and the recombinant proteins have been characterized to some extent. In this work, we report on the specific activity and the quantumyield of bioluminescence reaction as well as the absorbance characteristics of high-purity recombinant berovin. To determine those, we applied the amino acid composition analysis to accurately measure berovin concentration and the recombinant aequorin as a light standard to convert relative light units to quanta. The extinction coefficient of 1% berovin solution at 435 nm was found to be 1.82. The one can be employed to precisely determine the protein concentration of active photoproteins from other ctenophore species. The specific activity and the bioluminescence quantum yield were respectively found to be 1.98 x 10(15) quanta/mg and 0.083. These values appeared to be several times lower than those of the cnidarian photoproteins, which is obviously due to differences in amino acid environments of the substrate in active sites of these photoproteins. (C) 2022 Elsevier Inc. All rights reserved.

Automated summary

The bioluminescence of ctenophores is controlled by light-sensitive Ca2+-regulated photoproteins, which have been cloned and characterized from four different species. The specific activity, quantum yield, and absorbance characteristics of recombinant berovin were investigated, with values found to be lower than cnidarian photoproteins. The study provides insight into the differences in amino acid environments between ctenophore and cnidarian photoproteins.