A haloarchaeal ferredoxin electron donor that plays an essential role in nitrate assimilation

Basilio Zafrilla, Rosa María Martínez‑Espinosa, Mari­a José Bonete, Julea N. Butt, David J. Richardson, Andrew J. Gates

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Abstract

In the absence of ammonium, many organisms, including the halophilic archaeon Haloferax volcanii DS2 (DM3757), may assimilate inorganic nitrogen from nitrate or nitrite, using a ferredoxin-dependent assimilatory NO3-/NO2- reductase pathway. The small acidic ferredoxin Hv-Fd plays an essential role in the electron transfer cascade required for assimilatory nitrate and nitrite reduction by the cytoplasmic NarB- and NirA-type reductases respectively. UV–visible absorbance and EPR spectroscopic characterization of purified Hv-Fd demonstrate that this protein binds a single [2Fe–2S] cluster, and potentiometric titration reveals that the cluster shares similar redox properties with those present in plant-type ferredoxins.
Original languageEnglish
Pages (from-to)1844-1848
Number of pages5
JournalBiochemical Society Transactions
Volume39
Issue number6
DOIs
Publication statusPublished - 2011

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