ABSTRACT
The recent crystallographic characterization of NrfAs from Sulfurospirillum deleyianum, Wolinella succinogenes, Escherichia coli and Desulfovibrio desulfuricans allows structurally conserved regions to be identified. Comparison of nitrite and sulphite reductase activities from different bacteria shows that the relative activities vary according to organism. By comparison of both amino acid sequences and structures, differences can be identified in the monomer-monomer interface and the active-site channel; these differences could be responsible for the observed variance in substrate activity and indicate that subtle changes in the NrfA structure may optimize the enzyme for different roles.
Subject(s)
Cytochromes a1 , Cytochromes c1 , Desulfovibrio desulfuricans/enzymology , Epsilonproteobacteria/enzymology , Escherichia coli/enzymology , Nitrate Reductases , Protein Conformation , Wolinella/enzymology , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Binding Sites , Crystallography, X-Ray , Cytochrome c Group/chemistry , Cytochrome c Group/genetics , Cytochrome c Group/metabolism , Cytochromes a1/chemistry , Cytochromes a1/genetics , Cytochromes a1/metabolism , Cytochromes c1/chemistry , Cytochromes c1/genetics , Cytochromes c1/metabolism , Models, Molecular , Molecular Sequence Data , Nitrate Reductases/chemistry , Nitrate Reductases/genetics , Nitrate Reductases/metabolism , Sequence AlignmentABSTRACT
The recent structural characterization of the NrfA from Escherichia coli provides a framework to rationalize the spectroscopic and functional properties of this enzyme. Analyses by EPR and magnetic CD spectroscopies have been complemented by protein-film voltammetry and these are discussed in relation to the essential structural features of the enzyme.
