Brazilian researchers develop a bioluminescent enzyme

The discovery of a key enzyme in animal evolution that emits lights, similar to fireflies, paved the way for the unprecedented feat. The study was published in the journal Biochemistry.

By Marco Túlio Pires

Agência FAPESP – For the first time, researchers at Universidade Federal de São Carlos (UFSCar/Sorocaba) transformed a non-luminescent enzyme into an enzyme that can generate light using genetic engineering. The process was only made possible because of the discovery of an enzyme that is considered the “lost link” in the evolution of animals that emit light, such as fireflies, jelly fish and some beetles.

The results were published in the American Chemistry Society’s journal Biochemistry. FAPESP funded the study.

It is well known that light generation in live organisms, or bioluminescence, is only possible because of a group of enzymes called luciferases. For decades, however, scientists have attempted to discover how the evolution of these enzymes occurred, that is, how an enzyme that did not produce light became luminescent.

The group of Professor Vadim Viviani of UFSCar’s Bioluminescent Systems Biochemistry and Biotechnology Laboratory found this to have occurred in an enzyme considered to be a “distant cousin” of the luciferases. The enzyme is involved in the excretory system of the non-luminescent larvae of the Zophobas morio beetle, which is widely used as fish bait and known as mealworms or tenebrio.

Despite its lack of luster, the enzyme in the larval excretory system emits a very weak light when combined with luciferin from firefly (which the larvae do not possess).

“The quantity of light is so low that it is not considered luminescent; however, the molecular structure of the enzyme is similar to that of luciferase enzymes, placing it in the same family of enzymes,” said Viviani.

This distant cousin of the luciferases, now considered to be a link between the non-luminescence of the past and modern luciferases, is part of a larger group of enzymes called AMP/CoA-ligases, an ancient class found in all organisms and involved in the metabolism of organic acids.

“They are essential enzymes for all organisms, from bacteria to human beings,” said Viviani. However, their functions vary, depending on the tissue, organ or organisms in which they are found.

“In plants, for example, some of these enzymes are responsible for the process of pigmentation. In bacteria, they are involved in the metabolism of toxic compounds. In animals, the majority of them participate in the metabolism of fat. In fireflies, they produce light,” stated the researcher.

Viviani and Rogilene Prado, an FAPESP post doctoral fellow and researcher at the Science and Technology Center for Sustainability, discovered a structural “switch” that transformed AMP-ligase enzymes, until then dark, into luciferases, producers of light.

“With this, we managed to produce a completely new orange-colored luciferase light based on an AMP-ligase. We discovered which amino acids we should change to make the enzyme emit enough light to be considered luminescent,” related Viviani.

Although the color is not a novelty – though it is not a luciferase that naturally emits a similar light – the accomplishment is unprecedented. “This is the first time in the scientific literature that this process has been described,” affirmed Viviani.

Possible applications

The study paves the way for the development of bioluminescent AMP-ligases, luminous biosensors for toxic organic acids, for example, to determine whether an insect is resistant to a given insecticide of an acidic nature (recall that AMP-ligases, including luciferases, act on acidic compounds, detoxifying them in some cases), and luciferases that emit in several more intense colors than other enzymes.

Luciferases are broadly used as biomarkers, capable of helping in the detection of pathogenic cells, processes of infection and even the discovery of new drugs.

“The utilization of luminous biomarkers in metabolic processes increases our comprehension of how organisms work, which paths the substances take and whether a certain technique is successful,” explained Viviani. It is as if, suddenly, someone looking down on a city could illuminate only women or only men, or whoever is riding in cars, on motorcycles or buses or anyone wearing blue or yellow clothes.

Other participants in the study published in Biochemistry include UFSCar/Sorocaba biology student Deimison Neves, Professor Daichiro Kato of the University of Hyogo (Japan) and Professor João A. Barbosa of Universidade Federal de Brasília (UnB).

The group of researchers filed for a patent at the National Institute of Industrial Property (INPI), describing the development of a new luciferase based on AMP-ligases and the utilization of the enzyme as a biosensor for acidic compounds.