[NAD-dependent formate dehydrogenase of methylotrophic bacteria Pseudomonas sp. 101. III. Comparative analysis]

The comparative analysis of the primary and tertiary structures of NAD-dependent bacterial formate dehydrogenase (FDH) from methylotrophic bacterium Pseudomonas sp. 101 and a number of structurally characterized NAD-dependent dehydrogenases were performed. FDH has a highly conservative fold of the coenzyme binding domain. Position of the symmetry axis in the FDH molecule relative to the beta-sheets of its coenzyme binding domain with the respective sequences of the other NAD-dependent enzymes was performed on the basis of the spatial homology between these structures. Only one of the three amino acid residues previously thought to be conserved in the coenzyme binding domains of NAD-dependent dehydrogenases is preserved in the FDH molecule (Asp-221). Two glycine residues found in all previously studied dehydrogenases are substituted in FDH by Ala-198 and Pro-256, respectively. Position of the essential thiol of FDH (Cys-255) in the protein structure was established. It is suggested that Cys-255 is situated on or near polypeptide locus taking part in the conformational changes of the protein in the course of the catalysis.