Details

Autor(en) / Beteiligte

• Kartal, Boran
• Maalcke, Wouter J.
• de Almeida, Naomi M.
• Cirpus, Irina
• Gloerich, Jolein
• Geerts, Wim
• Op den Camp, Huub J. M.
• Harhangi, Harry R.
• Janssen-Megens, Eva M.
• Francoijs, Kees-Jan
• Stunnenberg, Hendrik G.
• Keltjens, Jan T.
• Jetten, Mike S. M.
• Strous, Marc

Titel

Molecular mechanism of anaerobic ammonium oxidation

Ist Teil von

• Nature (London), 2011-11, Vol.479 (7371), p.127-130

Ort / Verlag

London: Nature Publishing Group UK

Erscheinungsjahr

2011

Quelle

MEDLINE

Beschreibungen/Notizen

• Anammox pathway revealed Anammox, or anaerobic ammonium oxidation, is one of two important microbial processes that recycle fixed nitrogen back to the atmosphere. Less well studied than the other process (denitrification), anammox converts ammonia and nitrite into dinitrogen (N 2 ) gas. The complete biochemical and enzymatic mechanism of anammox has now been established. Nitric oxide and hydrazine are intermediate products in a pathway that involves three key enzymes — nitrite reductase, hydrazine synthase and hydrazine oxidoreductase. Two distinct microbial processes, denitrification and anaerobic ammonium oxidation (anammox), are responsible for the release of fixed nitrogen as dinitrogen gas (N 2 ) to the atmosphere 1 , 2 , 3 , 4 . Denitrification has been studied for over 100 years and its intermediates and enzymes are well known 5 . Even though anammox is a key biogeochemical process of equal importance, its molecular mechanism is unknown, but it was proposed to proceed through hydrazine (N 2 H 4 ) 6 , 7 . Here we show that N 2 H 4 is produced from the anammox substrates ammonium and nitrite and that nitric oxide (NO) is the direct precursor of N 2 H 4 . We resolved the genes and proteins central to anammox metabolism and purified the key enzymes that catalyse N 2 H 4 synthesis and its oxidation to N 2 . These results present a new biochemical reaction forging an N–N bond and fill a lacuna in our understanding of the biochemical synthesis of the N 2 in the atmosphere. Furthermore, they reinforce the role of nitric oxide in the evolution of the nitrogen cycle.