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How an enzyme in fireflies, click beetles and glow worms yields different colors

Date:
August 3, 2016
Source:
American Chemical Society
Summary:
The glow of fireflies at dusk is a welcome sign of summer. The same enzyme that helps give these familiar bugs their characteristic flash of yellow, yields red light in acidic conditions. Similar enzymes are responsible for red and green lights in other beetles. Despite years of study, however, scientists still don't know the molecular details of how the enzyme works. Now one team reports new insights into this mystery.
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The glow of fireflies at dusk is a welcome sign of summer. The same enzyme that helps give these familiar bugs their characteristic flash of yellow, yields red light in acidic conditions. Similar enzymes are responsible for red and green lights in other beetles. Despite years of study, however, scientists still don't know the molecular details of how the enzyme works. Now, in the ACS journal Biochemistry, one team reports new insights into this mystery.

Most people are familiar with the flash of fireflies. But perhaps less well known, but just as intriguing, are the displays of click beetles and railroad worms, which are a type of beetle larva. At night, two small dots on click beetles' backs glow like a pair of tiny green eyes peering in the dark. Railroad, or glow worms, exhibit a more complex pattern of both green and red lights. Taking advantage of this natural signaling, scientists have harnessed beetles' bioluminescence to help them see when certain genes are expressed, for example. But the structural and mechanistic factors contributing to beetles' glow have remained elusive. Vadim R. Viviani and colleagues wanted to gain a better understanding of these phenomena.

The researchers used modeling, mutations and spectral and kinetic studies to probe how changes to an enzyme called luciferase affect what color is emitted. Mutations to two particular parts of the enzyme produced a red glow. These parts display opposite charges, which attract each other and keep a "gate" closed where the light-emitting compound is generated. Under normal conditions, the enzyme active site remains closed restricting the entrance of water, which favors green light emission. But mutations and other alterations that break this attraction open the gate and allow water in. This relaxes the active site, resulting in the emission of light with lower energy in the red region.


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Journal Reference:

  1. Vadim R. Viviani, Aline F. Simões, Vanessa Resende Bevilaqua, Gabriele Verônica de Mello Gabriel, Frederico G. C. Arnoldi, Takashi Hirano. Glu311 and Arg337 stabilize a closed conformation and provide a critical catalytic base and countercation for green bioluminescence in beetle luciferases. Biochemistry, 2016; DOI: 10.1021/acs.biochem.6b00260

Cite This Page:

American Chemical Society. "How an enzyme in fireflies, click beetles and glow worms yields different colors." ScienceDaily. ScienceDaily, 3 August 2016. <www.sciencedaily.com/releases/2016/08/160803111756.htm>.
American Chemical Society. (2016, August 3). How an enzyme in fireflies, click beetles and glow worms yields different colors. ScienceDaily. Retrieved May 27, 2017 from www.sciencedaily.com/releases/2016/08/160803111756.htm
American Chemical Society. "How an enzyme in fireflies, click beetles and glow worms yields different colors." ScienceDaily. www.sciencedaily.com/releases/2016/08/160803111756.htm (accessed May 27, 2017).

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