The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress
Jason C. Crack, Basema K. Balasiny, Sophie P. Bennett, Matthew D. Rolfe, Afonso V. Torre Do Vale Froes, Fraser MacMillan, Jeffrey Green, Jeffrey A. Cole, Nick E. Le Brun
Abstract
, measured for the di-ferrous form, was ∼90 μM, well within the intracellular nitrite concentration range. The vicinal di-cysteine motif, located in the N-terminal domain of YtfE, was shown to function in the delivery of electrons to the di-iron center. Notably, YtfE exhibited very low NO reductase activity and was only able to act as an iron donor for reconstitution of apo-ferredoxin under conditions that damaged its di-iron center. Thus, YtfE is a high-affinity, low-capacity nitrite reductase that we propose functions to relieve nitrosative stress by acting in combination with the co-regulated NO-consuming enzymes Hmp and Hcp.