Structure-function relationship of assimilatory nitrite reductases from the leaf and root of tobacco based on high-resolution structures.

ABSTRACT: Tobacco expresses four isomers of assimilatory nitrite reductase (aNiR), leaf-type (Nii1 and Nii3), and root-type (Nii2 and Nii4). The high-resolution crystal structures of Nii3 and Nii4, determined at 1.25 and 2.3 Å resolutions, respectively, revealed that both proteins had very similar structures. The Nii3 structure provided detailed geometries for the [4Fe-4S] cluster and the siroheme prosthetic groups. We have generated two types of Nii3 variants: one set focuses on residue Met175 (Nii3-M175G, Nii3-M175E, and Nii3-M175K), a residue that is located on the substrate entrance pathway; the second set targets residue Gln448 (Nii3-Q448K), a residue near the prosthetic groups. Comparison of the structures and kinetics of the Nii3 wild-type (Nii3-WT) and the Met175 variants showed that the hyd

SUBMITTER: Nakano S 

PROVIDER: S-EPMC3375439 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature