GTP as an enzymatic synchronizer

Synchronizer is the key component of modern automobile gearbox, which coordinates the deceleration and acceleration of two groups of gears. In industry, synchronizer is composed of several components with fine structure. Here, we show that guanosine triphosphate (GTP) has the property of enzyme synchronizer. Through cryo-electron microscopy (cryo-EM) and 3D variability analysis, we obtain the full spectrum conformation of CTP synthase at near atomic resolution. In the catalytic process of CTP synthase, we find that GTP synchronizes the reaction of two independent domains, namely, glutamine-dependent aminotransferase (GAT) domain and amidoligase (AL) domain. The wing structure acts as a striker, and then stimulates the intermediate ammonia to complete the catalytic cycle through the internal gas channel. Different from being degraded to regulate tubulins or G-proteins, GTP acts as an enzymatic synchronizer to coordinate the reactions catalyzed by the two independent domains of CTP synthase.

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