Formimidoylglutamase (N-formimidoyl-L-glutamate formimidoylhydrolase; formiminoglutamase; N-formiminoglutamate hydrolase; N-formimino-L-glutamate formiminohydrolase; HutE; EC 3.5.3.8) is a metalloenzyme that catalyzes hydrolysis of N-formimidoyl-L-glutamate to L-glutamate and formamide. This enzyme is involved in histidine degradation, requiring Mn as a cofactor while glutathione may be required for maximal activity. In Pseudomonas PAO1, mutation studies show that histidine degradation proceeds via a 'four-step' pathway if the 'five-step' route is absent and vice versa; in the four-step pathway, formiminoglutaminase (HutE, EC 3.5.3.8) directly converts formiminoglutamate (FIGLU) to L-glutamate and formamide in a single step. Formiminoglutamase has traditionally also been referred to as HutG; however, formiminoglutamase is structurally and mechanistically unrelated to N-formyl-glutamate deformylase (also called HutG). Phylogenetic analysis has suggested that HutE was acquired by horizontal gene transfer from a Ralstonia-like ancestor.
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