Pyridine Nucleotide Complexes with Bacillus anthracis Coenzyme A-Disulfide Reductase: A Structural Analysis of Dual NAD(P)H Specificity.

We have recently reported that CoASH is the major low-molecular weight thiol in Bacillus anthracis [Nicely, N. I., Parsonage, D., Paige, C., Newton, G. L., Fahey, R. C., Leonardi, R., Jackowski, S., Mallett, T. C., and Claiborne, A. (2007) Biochemistry 46, 3234−3245], and we have now characterized the kinetic and redox properties of the B. anthracis coenzyme A-disulfide reductase (CoADR, BACoADR) and determined the crystal structure at 2.30 A resolution. While the Staphylococcus aureus and Borrelia burgdorferi CoADRs exhibit strong preferences for NADPH and NADH, respectively, B. anthracis CoADR can use either pyridine nucleotide equally well. Sequence elements within the respective NAD(P)H-binding motifs correctly reflect the preferences for S. aureus and Bo. burgdorferi CoADRs, but leave questions as to how BACoADR can interact with both pyridine nucleotides. The structures of the NADH and NADPH complexes at ca. 2.3 A resolution reveal that a loop consisting of residues Glu180-Thr187 becomes ordered and...