A suicide termite species from French Guiana carries a backpack filled with volatile toxins, ready to explode at a moment’s notice to protect its colony.
The suicide termites have evolved a unique defense mechanism, carrying a backpack filled with liquid toxins that can be activated to explode and poison enemies in the process. Now, scientists are exploring the mystery of how these termites carry this deadly backpack and trigger it when needed, as reported by Live Science on September 3rd.
A Neocapritermes taracua termite. (Photo: Aleš Buček).
In 2012, researchers discovered that older Neocapritermes taracua worker termites are equipped with backpacks that explode when threatened. These worker termites have a special gland in their abdomen that gradually secretes a blue enzyme called laccase BP76 into a pouch on their back. As they age, these termites accumulate a backpack filled with crystals of this blue copper compound. When threatened, the worker termites rub their bodies together, mixing the enzyme with secretions from their salivary gland. The result is a sticky liquid rich in extremely toxic benzoquinone compounds that can paralyze or kill predators.
However, researchers were puzzled about how BP76 can maintain a solid state while stored on the termite’s back and be ready to react instantly when rubbed together. A new study published in the journal Structure explores this mystery by providing the first high-resolution crystal structure of this enzyme. The three-dimensional structure of the enzyme reveals that BP76 has diverse stabilization mechanisms, according to lead researcher Jana Škerlová from the Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences. The enzyme’s compact folding helps prevent degradation over time. An additional protective layer comes from sugar molecules attached to the protein, forming a protective shield that stabilizes the structure.
One of the most interesting features of BP76 is the unusual strong chemical bond between two amino acids, lysine and cysteine, near the enzyme’s active site. This bond is not only common in enzymes but also plays a crucial role in maintaining the structure of BP76, especially when the enzyme is stored in a solid state on the termite’s back. The bond acts like a locking mechanism, ensuring that the enzyme can maintain its shape and full activity, ready to deploy instantly when the termite needs to protect its colony.
The ability to store and accumulate the enzyme stably as termites age has significant implications for colony protection. Previous studies have hypothesized that as the jaws of termites wear down over time, older termites may not forage or maintain the colony as effectively as younger ones. With explosive backpacks, older termites provide a last-ditch lethal measure to keep the colony safe.
