metallochaperones

Metallochaperones

A family of proteins that shuttle metal ions to specific sites within a cell. The target sites for metal delivery include a number of metalloenzymes, or proteins that bind metal ions, such as copper, zinc, or iron, and use these ions as cofactors to carry out essential biochemical reactions. Metallochaperones escort the ion to a specific intracellular location and facilitate incorporation of the metal into designated metalloenzymes. See Cell (biology)

The bulk of current knowledge on metallochaperones is restricted to copper, although it is reasonable to assume that a distinct class of proteins is responsible for the incorporation of other metal ion cofactors into metalloenzymes. Among the metallochaperones that have been studied in detail are a family of three copper chaperones. These molecules operate in eukaryotic (nucleated) cells to direct copper to distinct intracellular locations: the mitochondria, the secretory pathway, and the cytosol.

Intracellular copper is normally present at exquisitely low levels, and activation of copper enzymes is wholly dependent upon copper chaperones. Copper not only is an essential nutrient but also is quite toxic to living cells, and elaborate detoxification mechanisms prevent the free metal ion from accumulating to any substantial degree. The copper-requiring metalloenzymes cannot compete for these vanishingly low levels of available metal, explaining the requirement for the copper metallochaperones.

metallochaperones

[mə‚tal·ō′shap·ə‚rōnz]
(biochemistry)
Metalloproteins that aid in the insertion of the appropriate metal ion into a metalloenzyme.
A family of proteins that shuttles metal ions to specific intracellular locations where metalloenzymes bind to the metal ions and use them as cofactors to carry out essential biochemical reactions.
References in periodicals archive ?
Plants regulate the intercellular copper level by rectifying its uptake and declining the free intercellular copper concentrations by metallochaperones. These are Cu-binding soluble proteins which transport it to the sections of the plant cells where they are needed the most [56].
Metallochaperones, "An intracellular shuttle service for 422 metal ions," Journal of Biological Chemistry, vol.
Since metallochaperones and their targets share a metallochaperone domain, a zinc chaperone that binds to YiiP and transfers zinc might exist.
These products include a variety of participants, ranging from translocases, translational activators, and molecular chaperones to metallochaperones and enzymes involved in the biosynthesis of heme A [84].
This is accomplished through action of the metallochaperones SCO1 and SCO2; both have independent functions in incorporating copper into the [Cu.sub.A] site of COX II [121-123].
Enzyme promiscuity, copper metallochaperones, chemical approaches to glycobiology, and somatic mitochondrial DNA mutations in mammalian aging are some other areas explored.
In the new study, researchers found that three-dimensional structure of TM bound to copper-loaded metallochaperones. The drug sequesters the chaperone and its bound copper, preventing both from carrying out their normal functions in the cell.
In addition to transporters, plants also contain a class of molecules termed the metallochaperones that bind metals and facilitate their transport to target proteins/sites.
The metallochaperone Atoxl plays a critical role in perinatal copper homeostasis.
Because most transition metals are dangerous for cells, they exist inside the cells bound to storage proteins or are transferred to the enzymes with the help of special metallochaperones. Such a model has been developed for copper, and undoubtedly similar mechanisms exist for other essential metals (O'Halloran and Culotta 2000).