Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus.

Marie Lofstad, Ingvild Gudim, Marta Hammerstad, Åsmund Kjendseth Røhr, Hans-Petter Hersleth

Biochemistry 2016 Sep 13

filter terms:

To reduce ribonucleotides to deoxyribonucleotides, the manganese-bound form of class Ib ribonucleotide reductase (RNR) must be activated via a pathway that involves redox protein(s). The reduced flavoprotein NrdI is an important protein in this pathway, as it reduces dioxygen to superoxide. Superoxide then reacts with the RNR Mn(II)2 site to generate a tyrosyl radical that is required for catalysis. A native NrdI reductase has not yet been identified. We herein demonstrate through kinetic and spectroscopic studies that an endogenous flavodoxin reductase can function as the NrdI reductase in Bacillus cereus. When the flavodoxin reductase reduces NrdI, tyrosyl radical formation in RNR is promoted under aerobic conditions, significantly increasing the radical yield. Thus, a missing piece of the class Ib RNR NrdI redox pathway has finally been identified.

Citation

Marie Lofstad, Ingvild Gudim, Marta Hammerstad, Åsmund Kjendseth Røhr, Hans-Petter Hersleth. Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus. Biochemistry. 2016 Sep 13;55(36):4998-5001