Second Rhagophthalmid Luciferase Cloned from Chinese Glow-worm Menghuoius giganteus (Rhagophthalmidae: Elateroidea).

The pH-insensitive beetle luciferases cloned from Rhagophthalmidae, Phengodidae, and Elateridae exhibit great potential application as reporter assays for monitoring gene expression. At present, however, only one luciferase has been reported from the enigmatic and predominantly Asian distributed luminous family Rhagophthalmidae. Here, we cloned the second rhagophthalmid luciferase from the Chinese glow-worm Menghuoius giganteus (Rhagophthalmidae: Elateroidea) by combining reverse transcription polymerase chain reaction (RT-PCR) with rapid amplification of complementary DNA ends (RACE). The luciferase consisted of 546 amino acids and showed high identity to that of Rhagophthalmus ohbai (90.4%). The recombinant M. giganteus luciferase was produced in vitro and exhibited significant bioluminescent activity under neutral conditions (pH 7.8), with low KM for D-luciferin (2.2 µm) and ATP (53 µm). Activity was highest at 10°C and inactivation occurred at 45°C. This luciferase showed pH-insensitivity and maximum emission spectrum at 560 nm. Phylogenetic analyses based on the deduced amino acids indicated a close relationship between the M. giganteus luciferase and that of R. ohbai. These results increase our understanding of rhagophthalmid luciferases and provide a new resource for the application of luciferases.

Cloning and Characterization of Luciferase from the Chinese Firefly Lamprigera yunnana.

Lamprigera (Lampyridae) is a small genus with only 17 species distributing in Asian countries. Its larviform females and alate males can produce continuously strong yellow-green light at night. However, no luciferase gene was reported for this genus and its subfamily-level phylogenetic position still remains uncertain. Here, we cloned the luciferase gene from one Chinese species, Lamprigera yunnana, by reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE). This luciferase includes 551 deduced amino acids (AA) with the sequence identity of 71.8-76.8%, 67.5-70.7%, 68.4-75.3%, 77.8% and 59.5% to those from Lampyrinae, Luciolinae, Ototretinae, Cyphonocerinae and Photurinae, respectively. Phylogenetic analyses of deduced AA of luciferases suggest that Lamprigera locates outside Lampyrinae, in which it was originally placed in traditional taxonomy. The luciferase was produced in vitro as recombinant protein, and its biochemical properties were characterized. It possesses significant luminescence activity at pH 7.8, and its KM for D-luciferin and ATP are 61 µm and 122 µm, respectively. It shows the highest activity at 37°C and is completely inactivated at 55°C. It is pH-sensitive with the maximum emission spectrum of 566 nm at pH 7.8. Our data provide new insights into Lamprigera luciferase and its phylogenetic position.