KEGG   PATHWAY: rn00910
rn00910                     Pathway                                
Nitrogen metabolism
The biological process of the nitrogen cycle is a complex interplay among many microorganisms catalyzing different reactions, where nitrogen is found in various oxidation states ranging from +5 in nitrate to -3 in ammonia. The core nitrogen cycle involves four reduction pathways and two oxidation pathways. Nitrogen fixation [MD:M00175] is the process of reducing atmospheric molecular nitrogen to ammonia, a biologically useful reduced form incorporated into amino acids and other vital compounds. The ability of fixing atmospheric nitrogen by the nitrogenase enzyme complex is present in restricted prokaryotes (diazotrophs). The other reduction pathways are assimilatory nitrate reduction [MD:M00531] and dissimilatory nitrate reduction [MD:M00530] both for conversion to ammonia, and denitrification [MD:M00529]. Denitrification is a respiration in which nitrate or nitrite is reduced as a terminal electron acceptor under low oxygen or anoxic conditions, producing gaseous nitrogen compounds (N2, NO and N2O) to the atmosphere. The two oxidation pathways are nitrification [MD:M00528] and anaerobic ammonium oxidation (anammox) [MD:M00973]. Nitrification is the oxidation of ammonia (NH3) with oxygen into nitrite followed by the oxidation of nitrite into nitrate. The first step is performed by ammonia-oxidizing microorganisms (e.g., Nitrosomonas and Nitrosococcus) and the second step by nitrite-oxidizing microorganisms (e.g., Nitrobacter). Anammox is a biochemical process of oxidizing ammonium (NH4+) into dinitrogen gas (N2) using nitrite as an electron acceptor. It occurs in the anammoxosome, a membrane bound compartment inside the cytoplasm, of anammox bacteria (e.g., Planctomycetes).
Metabolism; Energy metabolism
Pathway map
rn00910  Nitrogen metabolism

M00175  Nitrogen fixation, nitrogen => ammonia [PATH:rn00910]
M00528  Nitrification, ammonia => nitrite [PATH:rn00910]
M00529  Denitrification, nitrate => nitrogen [PATH:rn00910]
M00530  Dissimilatory nitrate reduction, nitrate => ammonia [PATH:rn00910]
M00531  Assimilatory nitrate reduction, nitrate => ammonia [PATH:rn00910]
M00804  Complete nitrification, comammox, ammonia => nitrite => nitrate [PATH:rn00910]
M00973  Anammox, nitrite + ammonia => nitrogen [PATH:rn00910]
Other DBs
GO: 0006807
R00021  L-glutamate:ferredoxin oxidoreductase (transaminating)
R00025  ethylnitronate:oxygen 2-oxidoreductase (nitrite-forming)
R00093  L-glutamate:NAD+ oxidoreductase (transaminating)
R00114  L-glutamate:NADP+ oxidoreductase (transaminating)
R00143  ammonia:NAD+ oxidoreductase
R00148  ammonia,ubiquinol:oxygen oxidoreductase
R00149  Carbon-dioxide:ammonia ligase (ADP-forming,carbamate-phosphorylating)
R00243  L-glutamate:NAD+ oxidoreductase (deaminating)
R00248  L-glutamate:NADP+ oxidoreductase (deaminating)
R00253  L-Glutamate:ammonia ligase (ADP-forming)
R00294  nitrous-oxide:ferricytochrome-c oxidoreductase
R00524  Formamide amidohydrolase
R00540  Nitrile aminohydrolase
R00783  nitric-oxide:ferricytochrome-c oxidoreductase
R00785  nitric-oxide:oxidized azurin oxidoreductase
R00787  ammonia:NAD+ oxidoreductase
R00789  ammonia:NADP+ oxidoreductase
R00790  Ammonia:ferredoxin oxidoreductase
R00791  nitrite:ferredoxin oxidoreductase
R00794  nitrite:NAD+ oxidoreductase
R00796  nitrite:NADP+ oxidoreductase
R00798  nitrite:acceptor oxidoreductase
R01395  ATP:carbamate phosphotransferase
R02492  nitrous-oxide:NAD+ oxidoreductase
R02804  nitrogen:ferricytochrome-c oxidoreductase (N2O-forming)
R03071  ferrocytochrome:nitrate oxidoreductase
R03546  carbamate hydro-lyase
R05185  reduced ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
R05186  reduced flavodoxin:dinitrogen oxidoreductase (ATP-hydrolysing)
R05712  ammonia:ferricytochrome-c oxidoreductase
R07174  hydrazine:ferricytochrome c oxidoreductase
R09446  nitrous-oxide:NADP+ oxidoreductase
R09497  nitrite:quinone oxidoreductase
R09799  hydrazine:ferricytochrome-c oxidoreductase
R10092  carbonate hydro-lyase (carbon-dioxide-forming)
R10164  hydroxylamine:ferricytochrome-c oxidoreductase
R10230  hydroxylamine:oxygen oxidoreductase
R10388  nitroalkane:oxygen oxidoreductase
R10389  nitroalkane:oxygen oxidoreductase
R12084  ferredoxin:dinitrogen oxidoreductase (ATP-hydrolysing, vanadium-dependent)
C00011  CO2
C00014  Ammonia
C00025  L-Glutamate
C00058  Formate
C00064  L-Glutamine
C00088  Nitrite
C00169  Carbamoyl phosphate
C00192  Hydroxylamine
C00244  Nitrate
C00288  HCO3-
C00488  Formamide
C00533  Nitric oxide
C00697  Nitrogen
C00726  Nitrile
C00887  Nitrous oxide
C01417  Cyanate
C01563  Carbamate
C05361  Hydrazine
C06058  Nitroalkane
Scott JD, Ludwig RA
Azorhizobium caulinodans electron-transferring flavoprotein N electrochemically couples pyruvate dehydrogenase complex activity to N2 fixation.
Microbiology 150:117-26 (2004)
Kneip C, Lockhart P, Voss C, Maier UG
Nitrogen fixation in eukaryotes--new models for symbiosis.
BMC Evol Biol 7:55 (2007)
Whittaker M, Bergmann D, Arciero D, Hooper AB
Electron transfer during the oxidation of ammonia by the chemolithotrophic bacterium Nitrosomonas europaea.
Biochim Biophys Acta 1459:346-55 (2000)
Cabello P, Roldan MD, Moreno-Vivian C
Nitrate reduction and the nitrogen cycle in archaea.
Microbiology 150:3527-46 (2004)
Stolz JF, Basu P
Evolution of nitrate reductase: molecular and structural variations on a common function.
Morozkina EV, Zvyagilskaya RA
Nitrate reductases: structure, functions, and effect of stress factors.
Biochemistry (Mosc) 72:1151-60 (2007)
Jetten MS, Niftrik L, Strous M, Kartal B, Keltjens JT, Op den Camp HJ
Biochemistry and molecular biology of anammox bacteria.
Crit Rev Biochem Mol Biol 44:65-84 (2009)
Luesken FA, Wu ML, Op den Camp HJ, Keltjens JT, Stunnenberg H, Francoijs KJ, Strous M, Jetten MS
Effect of oxygen on the anaerobic methanotroph 'Candidatus Methylomirabilis oxyfera': kinetic and transcriptional analysis.
Environ Microbiol 14:1024-34 (2012)
Daims H, Lebedeva EV, Pjevac P, Han P, Herbold C, Albertsen M, Jehmlich N, Palatinszky M, Vierheilig J, Bulaev A, Kirkegaard RH, von Bergen M, Rattei T, Bendinger B, Nielsen PH, Wagner M
Complete nitrification by Nitrospira bacteria.
Nature 528:504-9 (2015)
van Kessel MA, Speth DR, Albertsen M, Nielsen PH, Op den Camp HJ, Kartal B, Jetten MS, Lucker S
Complete nitrification by a single microorganism.
Nature 528:555-9 (2015)
rn00220  Arginine biosynthesis
rn00250  Alanine, aspartate and glutamate metabolism
rn00460  Cyanoamino acid metabolism
rn00630  Glyoxylate and dicarboxylate metabolism
rn00680  Methane metabolism
rn00720  Carbon fixation pathways in prokaryotes
KO pathway

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