Team:Tokyo-NoKoGen/Project-4
The main component of ExTermite Coli is G3DH, which catalyzes the reaction to produce toxic material to termite. G3DH is one of an oxidoreductase and it requires substances which can receive electrons to function. Even though the G3DH expressed in E. coli under aerobic condition and can turn over to function correctly, there is no proof of functioning of G3DH in termite’s body.( See Details)
However, we think there is a possibility that an electron acceptor for G3DH exists inside termites.
During digestion of cellulose, termite also decomposes lignocellulose, which is contained in wood. One of components of lignocellulose is lignin, which is degradation product of lignocellulose. When lignin is produced, quinone, a possible electron acceptor of G3DH, is also produced.
Based on our hypothesis, we confirmed whether the ExTermite Coli could work in the termite’s gut in the experiments using electrode.
Therefore, in an aerobic condition, G3DH may donate electron to an electron acceptor in respiratory chain of E. coli and its cofactor may be re-oxidized as PQQ-dependent glucose oxidase. However, as inside of termite gut is anaerobic, the respiratory chain does not work. Therefore, reduced FAD cannot donate electron to electron acceptor.
For that reason, in order that G3DH continues to work in termite gut, extracellular electron acceptor should exist.
Electron from the reaction of trehalose oxidation was transported from FAD to electron receptor. After an electron receptor received electrons, electron receptor was oxidized and stored on the electrode. And then, after applying potential, an electron receptor was changed from oxidized to reduced form. At that time, electrons are transported to the electrode and we can observe response current.
In this experiment, we use screen printed carbon electrode (SPCE). This is one of an electrode used for sensor of medical equipment. Using this type of electrode, we can detect small electrical response to see the activity of enzymes. Also, only little amount of substrate is needed to experiment. It is great advantage for this experiment because we are no able to extract large amount of gut solution from tiny termites.
All together, it is indicated that ExTermite Coli can produce metabolic pathway inhibitors in termite’s gut.