Copper uptake regulation

Harland, A.D. and N.R. Nganro. 1990. Copper uptake by the sea anemone Anemonia viridis and the role of zooxanthellae in metal regulation. Mar Biol. 104 297-301. 

B. Regulation of Copper Uptake and Intracellular Copper Levels... 154... 

Regulation of copper uptake has been studied in most detail in the yeast Saccharomyces cerevisiae. Uptake of Cu + is similar to fhaf of Fe. The same plasma membrane reducfase system, consisting of proteins Frelp and Fre2p (encoded by genes FRE1 and FRET), acts to reduce both Fe + and These two... 

Because of their importance in the activity of many enzymes, bacteria have had to develop efficient uptake systems for copper and zinc. However, since both of these metals are toxic in excess, their intracellular content must be tightly regulated. Copper uptake homeostasis has been most extensively studied in the Gram-positive... 

R. Welch, W. Norvell, S. Schaefer, J. Shaff, and L. Kochian, Induction of iron (111) and copper (11) reduction in pea Pisiim. sativum L.) roots by Fe and Cu status. Does the root-cell plasma Fe(lll) reductase perform a general role in regulating cation uptake Planta 190 555 (1993). 

Zia, S. and M.A. Alikhan. 1989. A laboratory study of the copper and nickel uptake and regulation in a copper-tolerant decapod, Cambarus bartoni (Fabricus) (Decapoda, Crustaceana). Arch. Inter. Physiol. Biochimie 97 211-219. 

Sunda, W. G. and Huntsman, S. A. (1995). Regulation of copper concentration in the oceanic nutricline by phytoplankton uptake and regeneration cycles, Limnol. Oceanogr., 40, 132-137. 

Many aquatic organisms exhibit an ability to concentrate a variety of trace elements and this ability has been identified as a function of the tendency of the elements to be complexed by ligands (159). The alkaline earth metals are poorly com-plexed in relation to the transition metals, copper, nickel, cobalt, zinc and manganese. The actinides should be regarded as members of an intermediate group. It has been suggested by Martin (160) that at least five mechanisms may regulate the uptake of metals by marine biota. These are... 

An adult human ingests 2-5 mg of copper per day, about 30% of which is absorbed. The total body content of copper is 100 mg ( 2 x 10 4 mol/kg), and both uptake and excretion (via the bile) are regulated. Since an excess of copper is toxic, regulation is important. 

Copper ion homeostasis in prokaryotes involves Cu ion efflux and sequestration. The proteins involved in these processes are regulated in their biosynthesis by the cellular Cu ion status. The best studied bacterial Cu metalloregulation system is found in the gram-positive bacterium Enterococcus hirae. Cellular Cu levels in this bacterium control the expression of two P-type ATPases critical for Cu homeostasis (Odermatt and Solioz, 1995). The CopA ATPase functions in Cu ion uptake, whereas the CopB ATPase is a Cu(I) efflux pump (Solioz and Odermatt, 1995). The biosynthesis of both ATPases is regulated by a Cu-responsive transcription factor, CopY (Harrison et al., 2000). In low ambient Cu levels Cop Y represses transcription of the two ATPase genes. On exposure to Cu(I), CopY dissociates from promoter/operator sites on DNA with a for Cu of 20 jlM (Strausak and Solioz, 1997). Transcription of copA and copB proceeds after dissociation of CuCopY. The only other metal ions that induce CopY dissociation from DNA in vitro are Ag(I) and Cd(II), although the in vivo activation of copA and copB is specihc to Cu salts. The CuCopY complex is dimeric with two Cu(I) ions binding per monomer (C. T. Dameron, personal communication). The structural basis for the Cu-induced dissociation of CopY is unknown. Curiously, CopY is also activated in Cu-dehcient cells, but the mechanism is distinct from the described Cu-induced dissociation from DNA (Wunderh-Ye and Solioz, 1999). 

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