Comparison of CryoEM and X-ray structures of dimethylformamidase

Dimethylformamidase (DMFase) catalyzes the hydrolysis of dimethylformamide, an industrial solvent, introduced into the environment by humans. Recently, we determined the structures of dimethylformamidase by electron cryo microscopy and X-ray crystallography revealing a tetrameric enzyme with a mononuclear iron at the active site. DMFase from Paracoccus sp. isolated from a waste water treatment plant around the city of Kanpur in India shows maximal activity at 54 degrees C and is halotolerant. The structures determined by both techniques are mostly identical and the largest difference is in a loop near the active site. This loop could play a role in co-operativity between the monomers. A number of non-protein densities are observed in the EM map, which are modelled as water molecules. Comparison of the structures determined by the two methods reveals conserved water molecules that could play a structural role. The higher stability, unusual active site and negligible activity at low temperature makes this a very good model to study enzyme mechanism by cryoEM. (C) 2020 Elsevier Ltd. All rights reserved.

Automated summary

Dimethylformamidase (DMFase) catalyzes the hydrolysis of dimethylformamide, and recent studies have determined its tetrameric structure with a mononuclear iron at the active site. Isolated from Paracoccus sp. in India, this enzyme shows maximal activity at 54 degrees C and is halotolerant. Comparison of structures determined by electron cryo microscopy and X-ray crystallography reveals conserved water molecules which may play a structural role in the enzyme's mechanism.