Download Low temperature adaptation of luciferase in Tibetan firefly

Biogeography of Bioluminescent Organism
Yoshihiro OHMIYA*
Address: DAILAB, Biomedical Research Institute, AIST, Tsukuba, 305-8566, Japan
Email: [email protected]
Bioluminescence, the production of light without heat by living organisms, has elicited
the interest of scientists for a long time. The biological functions of bioluminescence are
thought to involve defence against predators, assistance in predation, communication in
reproduction, and metabolic and biochemical pathway by-product formation in organisms.
Bioluminescence reveals a diversity of organisms from bacteria to fish, because the
luciferins (substrates) of the various phylogenetically distant systems on unrelated
chemical classes and the luciferases (enzyme) based on different gene family. So, for
example, a biologist researches the behaviour, ecology, and taxonomy of bioluminescent
organisms to reveal their diversity. A chemist determines the luciferin structure and
analyses the chemical reaction to produce new chemiluminescent or fluorescent materials.
A biochemist explores a new luciferase from organisms to understand the metabolic
pathway and its mechanism, and a bioengineer develops a biotechnological tool by using
information from earlier bioluminescence research. Research on many bioluminescent
organisms has gradually revealed various aspects of this mysterious feature. In this
seminar, I talked about the biography of bioluminescent organisms for luminescent beetle
and ostracod.
Low temperature adaptation of luciferase in Tibetan firefly
Yasuo Mitani
Insects are the most diverse group of bioluminescence organisms, and more than 2,500
luminescent insects have been described. Most luminescent insects live in relatively
moderate climate area such as Europe, North and South America, and Asia. We recently
characterized the luciferase from a Fijian click beetle, which was the first report of
luciferase from Melanesian click beetle. In this study, we identified and characterized
the luciferase and luciferase-like genes from a Tibetan firefly Pyrocoelia sp. collected in
Shangri-La, China. Shangri-La is located in Tibetan Autonomous Prefecture within
Yunnan province, and its altitude is more than 3,300 meter high, where the average
summer temperature is lower than 15˚C. We observed that this Tibetan firefly produces
luminescence after sunset when the temperature is about 10˚C. We analyzed the mRNA
expression by RNA-seq using head, thorax, abdomen (without light organ), and light
organ tissue. We found one luciferase gene expressed specifically in the light organ.
This luciferase was almost identical to luciferase from fireflies Pyrocoelia pactoralis and
Pyrocoelia pygidialis. We synthesized the luciferase gene of Tibetan firefly and
analyzed its luciferase activity. The recombinant protein exhibited optimal activity
around neutral pH and showed maximum activity in low temperature compared to
known firefly luciferases. When the recombinant protein was put under higher
temperature such as 37˚C, the luciferase activity was lost in a couple of minutes. Further
characteristics including emission spectrum, kinetics analysis, and pH sensitivity will be
discussed.