Review
Cell biology of molybdenum in plants and humans

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Abstract

The transition element molybdenum (Mo) needs to be complexed by a special cofactor in order to gain catalytic activity. With the exception of bacterial Mo-nitrogenase, where Mo is a constituent of the FeMo-cofactor, Mo is bound to a pterin, thus forming the molybdenum cofactor Moco, which in different variants is the active compound at the catalytic site of all other Mo-containing enzymes. In eukaryotes, the most prominent Mo-enzymes are nitrate reductase, sulfite oxidase, xanthine dehydrogenase, aldehyde oxidase, and the mitochondrial amidoxime reductase. The biosynthesis of Moco involves the complex interaction of six proteins and is a process of four steps, which also requires iron, ATP and copper. After its synthesis, Moco is distributed to the apoproteins of Mo-enzymes by Moco-carrier/binding proteins. A deficiency in the biosynthesis of Moco has lethal consequences for the respective organisms. In humans, Moco deficiency is a severe inherited inborn error in metabolism resulting in severe neurodegeneration in newborns and causing early childhood death. This article is part of a Special Issue entitled: Cell Biology of Metals.

Highlights

► Mo needs to be complexed by a special cofactor in order to gain catalytic activity. ► The molybdenum cofactor (Moco) forms the active site of all eukaryotic Mo enzymes. ► Mo enzymes are an essential part of the global carbon, nitrogen and sulfur cycles. ► Moco is synthesized by a conserved pathway that consists of four steps. ► Iron and copper are involved in Mo metabolism in eukaryotes.

Abbreviations

AO
aldehyde oxidase
cPMP
cyclic pyranopterin monophosphate
Cu
copper
Fe
iron
Mo
molybdenum
Moco
molybdenum cofactor
MoBP
molybdenum cofactor binding protein
MPT
molybdopterin
NR
nitrate reductase
SO
sulfite oxidase
XDH
xanthine dehydrogenase
XO
xanthine oxidase

Keywords

Molybdenum cofactor
Molybdenum deficiency
Sulfite oxidase
Nitrate reductase
Xanthine dehydrogenase
Aldehyde oxidase

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This article is part of a Special Issue entitled: Cell Biology of Metals.