If an enzyme name is shown in bold, there is experimental evidence for this enzymatic activity.
Locations of Mapped Genes:
Synonyms: MCD biosynthesis, molybdopterin cytosine dinucleotide biosynthesis
|Superclasses:||Biosynthesis → Cofactors, Prosthetic Groups, Electron Carriers Biosynthesis|
The transition element molybdenum (Mo) has been long known as an essential micronutrient across the kingdoms of plants, animals, fungi and bacteria. However, molybdate itself is catalytically inactive and, with the exception of bacterial nitrogenase, needs to be activated through complexation by a special cofactor. There are several molybdenum cofactors, including molybdopterin (MPT), guanylyl molybdenum cofactor (MGD), cytidylyl molybdenum cofactor, and others [Rajagopalan92].
The chemical nature and biosynthesis of molybdenum cofactors have been investigated in detail in bacteria [Wuebbens95, Pitterle93a, Pitterle93, Rajagopalan92, SantamariaArauj04] and plants. All of the cofactors are synthesized from molybdopterin (MPT). The MPT structure is conserved in all organisms, and it has been demonstrated that its biosynthesis is preserved in bacteria and plants alike (see molybdenum cofactor biosynthesis). The variability of the molybdenum cofactors found in bacteria is achieved by the attachment of GMP, AMP, IMP, or CMP to the phosphate group of MPT.
In Escherichia coli, both guanylyl molybdenum cofactor and cytidylyl molybdenum cofactor are present. The mocA gene product molybdenum cofactor cytidylyltransferase catalyzes the transfer of the cytosine nucleotide from CTP, releasing the β- and γ-phosphates of CTP as pyrophosphate and forming cytidylyl molybdenum cofactor [Neumann09].
Two enzymes that utilize this cofactor have been identified in Escherichia coli: aldehyde dehydrogenase [Neumann09a] and two xanthine dehydrogenases - the xanthine dehydrogenase encoded by xdhABC, and the predicted xanthine dehydrogenase XdhD [Neumann09].
IobbiNivol13: Iobbi-Nivol C, Leimkuhler S (2013). "Molybdenum enzymes, their maturation and molybdenum cofactor biosynthesis in Escherichia coli." Biochim Biophys Acta 1827(8-9);1086-101. PMID: 23201473
Neumann09: Neumann M, Mittelstadt G, Seduk F, Iobbi-Nivol C, Leimkuhler S (2009). "MocA is a specific cytidylyl transferase involved in molybdopterin cytosine dinucleotide biosynthesis in Escherichia coli." J Biol Chem 284(33);21891-8. PMID: 19542235
Neumann09a: Neumann M, Mittelstadt G, Iobbi-Nivol C, Saggu M, Lendzian F, Hildebrandt P, Leimkuhler S (2009). "A periplasmic aldehyde oxidoreductase represents the first molybdopterin cytosine dinucleotide cofactor containing molybdo-flavoenzyme from Escherichia coli." FEBS J 276(10);2762-74. PMID: 19368556
Pitterle93: Pitterle DM, Rajagopalan KV (1993). "The biosynthesis of molybdopterin in Escherichia coli. Purification and characterization of the converting factor." J Biol Chem 268(18);13499-505. PMID: 8514782
Pitterle93a: Pitterle DM, Johnson JL, Rajagopalan KV (1993). "In vitro synthesis of molybdopterin from precursor Z using purified converting factor. Role of protein-bound sulfur in formation of the dithiolene." J Biol Chem 268(18);13506-9. PMID: 8514783
SantamariaArauj04: Santamaria-Araujo JA, Fischer B, Otte T, Nimtz M, Mendel RR, Wray V, Schwarz G (2004). "The tetrahydropyranopterin structure of the sulfur-free and metal-free molybdenum cofactor precursor." J Biol Chem 279(16);15994-9. PMID: 14761975
Wuebbens95: Wuebbens MM, Rajagopalan KV (1995). "Investigation of the early steps of molybdopterin biosynthesis in Escherichia coli through the use of in vivo labeling studies." J Biol Chem 270(3);1082-7. PMID: 7836363
Neumann11: Neumann M, Seduk F, Iobbi-Nivol C, Leimkuhler S (2011). "Molybdopterin dinucleotide biosynthesis in Escherichia coli: identification of amino acid residues of molybdopterin dinucleotide transferases that determine specificity for binding of guanine or cytosine nucleotides." J Biol Chem 286(2);1400-8. PMID: 21081498
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