Enzymes with opposite functions form complex

Abstract

Enzyme complexes usually make multistep processes easier by catalyzing sequential reactions, in which the product of one enzyme becomes the substrate for the next. In a new finding, researchers report an enzyme complex where the two interacting enzymes have opposite functions—one makes the metabolite glutamate and the other degrades it. When bound to each other, one of the enzymes inhibits the activity of the other. In this way, the complex has the effect of regulating the amount of the glutamate inside the bacterial cell. Researchers led by James S. Fraser of the University of California San Francisco and Dan S. Tawfik and Vijay Jayaraman of the Weizmann Institute of Science solved cryo-electron microscopy structures of a complex of the enzymes glutamate synthase (GltAB ) and glutamate dehydrogenase (GudB ) in Bacillus subtilis . The structures reveal that the two enzymes form a complex in which one of GltAB’s subunits blocks