title: Activation of the Class Ib Ribonucleotide Reductase by a Flavodoxin Reductase in Bacillus cereus.
abstract: 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.
authors: Section for Biochemistry and Molecular Biology, Department of Biosciences, University of Oslo , P.O. Box 1066, Blindern, NO-0316 Oslo, Norway.
authors: Marie
authors: M
authors: Lofstad
authors: Section for Biochemistry and Molecular Biology, Department of Biosciences, University of Oslo , P.O. Box 1066, Blindern, NO-0316 Oslo, Norway.
authors: Ingvild
authors: I
authors: Gudim
authors: Section for Biochemistry and Molecular Biology, Department of Biosciences, University of Oslo , P.O. Box 1066, Blindern, NO-0316 Oslo, Norway.
authors: Marta
authors: M
authors: Hammerstad
authors: Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences , P.O. Box 5003, NO-1432 Ås, Norway.
authors: Åsmund Kjendseth
authors: ÅK
authors: Røhr
authors: Section for Biochemistry and Molecular Biology, Department of Biosciences, University of Oslo , P.O. Box 1066, Blindern, NO-0316 Oslo, Norway.
authors: Hans-Petter
authors: HP
authors: Hersleth
mesh_terms: D001409:Bacillus cereus / Q000201:enzymology*; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D012264:Ribonucleotide Reductases / Q000378:metabolism*
chemical_list: D012264:Ribonucleotide Reductases; D009247:NADH, NADPH Oxidoreductases; C116041:flavodoxin NADPH oxidoreductase