A common catalytic mechanism for proteins of the HutI family.
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Imidazolonepropionase (HutI) (imidazolone-5-propanote hydrolase, EC 126.96.36.199) is a member of the amidohydrolase superfamily and catalyzes the conversion of imidazolone-5-propanoate to N-formimino-L-glutamate in the histidine degradation pathway. We have determined the three-dimensional crystal structures of HutI from Agrobacterium tumefaciens (At-HutI) and an environmental sample from the Sargasso Sea Ocean Going Survey (Es-HutI) bound to the product [ N-formimino-L-glutamate (NIG)] and an inhibitor [3-(2,5-dioxoimidazolidin-4-yl)propionic acid (DIP)], respectively. In both structures, the active site is contained within each monomer, and its organization displays the landmark feature of the amidohydrolase superfamily, showing a metal ligand (iron), four histidines, and one aspartic acid. A catalytic mechanism involving His265 is proposed on the basis of the inhibitor-bound structure. This mechanism is applicable to all HutI forms.
author list (cited authors)
Tyagi, R., Eswaramoorthy, S., Burley, S. K., Raushel, F. M., & Swaminathan, S.
complete list of authors
Tyagi, Rajiv||Eswaramoorthy, Subramaniam||Burley, Stephen K||Raushel, Frank M||Swaminathan, Subramanyam