ENTRY ko00910 Pathway NAME Nitrogen metabolism DESCRIPTION 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). CLASS Metabolism; Energy metabolism PATHWAY_MAP ko00910 Nitrogen metabolism MODULE M00175 Nitrogen fixation, nitrogen => ammonia [PATH:ko00910] M00528 Nitrification, ammonia => nitrite [PATH:ko00910] M00529 Denitrification, nitrate => nitrogen [PATH:ko00910] M00530 Dissimilatory nitrate reduction, nitrate => ammonia [PATH:ko00910] M00531 Assimilatory nitrate reduction, nitrate => ammonia [PATH:ko00910] M00804 Complete nitrification, comammox, ammonia => nitrite => nitrate [PATH:ko00910] M00973 Anammox, nitrite + ammonia => nitrogen [PATH:ko00910] DBLINKS GO: 0006807 ORTHOLOGY K01455 formamidase [EC:3.5.1.49] K02575 MFS transporter, NNP family, nitrate/nitrite transporter K15576 nitrate/nitrite transport system substrate-binding protein K15577 nitrate/nitrite transport system permease protein K15578 nitrate/nitrite transport system ATP-binding protein [EC:7.3.2.4] K15579 nitrate/nitrite transport system ATP-binding protein K00367 ferredoxin-nitrate reductase [EC:1.7.7.2] K10534 nitrate reductase (NAD(P)H) [EC:1.7.1.1 1.7.1.2 1.7.1.3] K00370 nitrate reductase / nitrite oxidoreductase, alpha subunit [EC:1.7.5.1 1.7.99.-] K00371 nitrate reductase / nitrite oxidoreductase, beta subunit [EC:1.7.5.1 1.7.99.-] K00374 nitrate reductase gamma subunit [EC:1.7.5.1 1.7.99.-] K02567 nitrate reductase (cytochrome) [EC:1.9.6.1] K02568 nitrate reductase (cytochrome), electron transfer subunit K00372 assimilatory nitrate reductase catalytic subunit [EC:1.7.99.-] K00360 assimilatory nitrate reductase electron transfer subunit [EC:1.7.99.-] K17877 nitrite reductase (NAD(P)H) [EC:1.7.1.4] K26139 nitrite reductase [NAD(P)H] large subunit [EC:1.7.1.4] K26138 nitrite reductase [NAD(P)H] small subunit [EC:1.7.1.4] K00361 nitrite reductase [NAD(P)H] [EC:1.7.1.4] K00362 nitrite reductase (NADH) large subunit [EC:1.7.1.15] K00363 nitrite reductase (NADH) small subunit [EC:1.7.1.15] K00366 ferredoxin-nitrite reductase [EC:1.7.7.1] K03385 nitrite reductase (cytochrome c-552) [EC:1.7.2.2] K15876 cytochrome c nitrite reductase small subunit K00368 nitrite reductase (NO-forming) [EC:1.7.2.1] K15864 nitrite reductase (NO-forming) / hydroxylamine reductase [EC:1.7.2.1 1.7.99.1] K04561 nitric oxide reductase subunit B [EC:1.7.2.5] K02305 nitric oxide reductase subunit C K15877 fungal nitric oxide reductase [EC:1.7.1.14] K00376 nitrous-oxide reductase [EC:1.7.2.4] K27148 nitric oxide dismutase K02586 nitrogenase molybdenum-iron protein alpha chain [EC:1.18.6.1] K02591 nitrogenase molybdenum-iron protein beta chain [EC:1.18.6.1] K02588 nitrogenase iron protein NifH K00531 nitrogenase delta subunit [EC:1.18.6.1] K22896 vanadium-dependent nitrogenase alpha chain [EC:1.18.6.2] K22897 vanadium-dependent nitrogenase beta chain [EC:1.18.6.2] K22898 vanadium nitrogenase delta subunit [EC:1.18.6.2] K22899 vanadium nitrogenase iron protein K20932 hydrazine synthase subunit [EC:1.7.2.7] K20933 hydrazine synthase subunit [EC:1.7.2.7] K20934 hydrazine synthase subunit [EC:1.7.2.7] K20935 hydrazine dehydrogenase [EC:1.7.2.8] K10944 methane/ammonia monooxygenase subunit A [EC:1.14.18.3 1.14.99.39] K10945 methane/ammonia monooxygenase subunit B K10946 methane/ammonia monooxygenase subunit C K05601 hydroxylamine reductase [EC:1.7.99.1] K10535 hydroxylamine dehydrogenase [EC:1.7.2.6] K00459 nitronate monooxygenase [EC:1.13.12.16] K19823 nitroalkane oxidase [EC:1.7.3.1] K01501 nitrilase [EC:3.5.5.1] K15371 glutamate dehydrogenase [EC:1.4.1.2] K00260 glutamate dehydrogenase [EC:1.4.1.2] K00261 glutamate dehydrogenase (NAD(P)+) [EC:1.4.1.3] K00262 glutamate dehydrogenase (NADP+) [EC:1.4.1.4] K01915 glutamine synthetase [EC:6.3.1.2] K00264 glutamate synthase (NADH) [EC:1.4.1.14] K00265 glutamate synthase (NADPH) large chain [EC:1.4.1.13] K00266 glutamate synthase (NADPH) small chain [EC:1.4.1.13] K00284 glutamate synthase (ferredoxin) [EC:1.4.7.1] K01948 carbamoyl-phosphate synthase (ammonia) [EC:6.3.4.16] K01725 cyanate lyase [EC:4.2.1.104] K00926 carbamate kinase [EC:2.7.2.2] K01672 carbonic anhydrase [EC:4.2.1.1] K18245 carbonic anhydrase 2 [EC:4.2.1.1] K18246 carbonic anhydrase 4 [EC:4.2.1.1] K01673 carbonic anhydrase [EC:4.2.1.1] K01674 carbonic anhydrase [EC:4.2.1.1] K01743 carbonic anhydrase [EC:4.2.1.1] COMPOUND C00007 Oxygen 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 REFERENCE PMID:14702404 AUTHORS Scott JD, Ludwig RA TITLE Azorhizobium caulinodans electron-transferring flavoprotein N electrochemically couples pyruvate dehydrogenase complex activity to N2 fixation. JOURNAL Microbiology 150:117-26 (2004) DOI:10.1099/mic.0.26603-0 REFERENCE PMID:17408485 AUTHORS Kneip C, Lockhart P, Voss C, Maier UG TITLE Nitrogen fixation in eukaryotes--new models for symbiosis. JOURNAL BMC Evol Biol 7:55 (2007) DOI:10.1186/1471-2148-7-55 REFERENCE PMID:11004450 AUTHORS Whittaker M, Bergmann D, Arciero D, Hooper AB TITLE Electron transfer during the oxidation of ammonia by the chemolithotrophic bacterium Nitrosomonas europaea. JOURNAL Biochim Biophys Acta 1459:346-55 (2000) DOI:10.1016/S0005-2728(00)00171-7 REFERENCE PMID:15528644 AUTHORS Cabello P, Roldan MD, Moreno-Vivian C TITLE Nitrate reduction and the nitrogen cycle in archaea. JOURNAL Microbiology 150:3527-46 (2004) DOI:10.1099/mic.0.27303-0 REFERENCE PMID:11921398 AUTHORS Stolz JF, Basu P TITLE Evolution of nitrate reductase: molecular and structural variations on a common function. JOURNAL Chembiochem 3:198-206 (2002) DOI:10.1002/1439-7633(20020301)3:2/3<198::AID-CBIC198>3.0.CO;2-C REFERENCE PMID:18021072 AUTHORS Morozkina EV, Zvyagilskaya RA TITLE Nitrate reductases: structure, functions, and effect of stress factors. JOURNAL Biochemistry (Mosc) 72:1151-60 (2007) DOI:10.1134/S0006297907100124 REFERENCE PMID:19247843 AUTHORS Jetten MS, Niftrik L, Strous M, Kartal B, Keltjens JT, Op den Camp HJ TITLE Biochemistry and molecular biology of anammox bacteria. JOURNAL Crit Rev Biochem Mol Biol 44:65-84 (2009) DOI:10.1080/10409230902722783 REFERENCE PMID:22221911 AUTHORS Luesken FA, Wu ML, Op den Camp HJ, Keltjens JT, Stunnenberg H, Francoijs KJ, Strous M, Jetten MS TITLE Effect of oxygen on the anaerobic methanotroph 'Candidatus Methylomirabilis oxyfera': kinetic and transcriptional analysis. JOURNAL Environ Microbiol 14:1024-34 (2012) DOI:10.1111/j.1462-2920.2011.02682.x REFERENCE PMID:26610024 AUTHORS 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 TITLE Complete nitrification by Nitrospira bacteria. JOURNAL Nature 528:504-9 (2015) DOI:10.1038/nature16461 REFERENCE PMID:26610025 AUTHORS van Kessel MA, Speth DR, Albertsen M, Nielsen PH, Op den Camp HJ, Kartal B, Jetten MS, Lucker S TITLE Complete nitrification by a single microorganism. JOURNAL Nature 528:555-9 (2015) DOI:10.1038/nature16459 REL_PATHWAY ko00220 Arginine biosynthesis ko00250 Alanine, aspartate and glutamate metabolism ko00460 Cyanoamino acid metabolism ko00630 Glyoxylate and dicarboxylate metabolism ko00680 Methane metabolism ko00720 Other carbon fixation pathways ///