Utilization
of S. cerevisiae mutants defective in high affinity copper uptake to
characterize copper transporters from plants and mammals.
Sergi Puig (1),
Vicente Sancenon (2), Lola Peñarrubia (2), Dennis J. Thiele (1)
(1) Dept. of Biological Chemistry, University of Michigan Med. Sch, 1301
Catherine Rd, Ann Arbor, MI 48109-0606, USA (spuig@umich.edu); (2) Departament
de Bioquimica i Biologia Molecular, Universitat de Valencia, Dr. Moliner 50,
Burjassot, Valencia, 46100 Spain.
Copper (Cu) is a
transition metal able to cycle between two redox states, oxidized Cu(I) and
reduced Cu(II). Virtually all organisms require Cu as a catalytic co-factor for
biological processes such as respiration, iron transport, oxidative stress
protection, hormone production, pigmentation, blood clotting and normal cell
growth and development. However, Cu also participates in redox reactions that
generate hydroxyl radicals, which cause catastrophic damage to lipids, proteins
and DNA. Therefore, cells have developed sophisticated homeostatic mechanisms
to accumulate sufficient but not toxic levels of Cu. The acquisition of Cu
across the plasma membrane represents a crucial step of regulation. Cu uptake
is mediated by a family of transporters (CTR1) conserved in yeast, mammals and
plants. S. cerevisiae is an excellent model system to study Cu transport and
distribution in eukaryotic cells. Here, we describe the use of yeast cells
defective in high affinity copper uptake (ctr1Δ mutants) to isolate and analyze
Cu transporters from other organisms. We recently showed the essential role of
conserved methionine residues in human Ctr1 (hCtr1) by complementation of the
respiratory defect of a yeast ctr1Δ strain. We have also used this strategy to
identify a family of Cu transporters (COPT1-COPT5) in the model plant Arabidopsis
thaliana.
We plan to use this approach to explore new genes involved in Cu homeostasis.