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Cu(ll)
Cu(l)
Cu
COPZ
COPY
High Cu
Low Cu
copY
copZ
copA
copB
COPY
Zn
(A)
Cyt- b o3
CueO
SOD
CueR
copA
cueO
CusCBA
CusR
CusCFBA
CusF
NDH-2
Cu(l)
Cu(ll)
(B)
FIGURE 13.4
Illustrations. of.copper. homeostasis. in. two. bacterial.models,. Enterococcus hirae .(Panel.A).and.
E. coli . (Panel. B). (white. rectangles. symbolize. copper. reductases,. gray. rectangles. are. copper.
transporters,.and.white.circles.represent.copper.targets).
Solioz.2005)..Structural.analysis.of.the.CopZ.chaperone,.via.NMR.spectros-
copy,.shows.that.in.addition.to.the.typical.metal.binding.domain.(MxCxxC).
this.protein.exhibits.a.βαββαβ.ATX-like.folding.pattern.(Wimmer.et.al..1999).
A.second.prokaryotic.model.for.studying.copper.transport.is.the.bacteria.
E. coli ..While.copper.homeostasis.is.not.well-known.in.these.Gram-negative.
bacteria,. targets. for. copper. include. a. Cu,Zn. SOD. in. the. periplasm. (Benov.
and.Fridovich.1994,.Gort.et.al..1999).as.well.as.cytochrome. bo 3 .that.is.classi-
ied.as.a.heme-copper.oxidase.(Figure.13.4B).(Osborne.et.al..1999)..Although.
there. is. the. requirement. of. copper. for. proper. function. of. these. enzymes,.
most.of.the.components.that.make.up.the.known.copper.traficking.system.
in. E. coli . function. in. detoxiication.. Copper. (II). ions. seem. to. pass. through.
the. outer. membrane. via. porins. and. are. then. reduced. to. Cu(I). by. the. cop-
per.reductase.NDH-2.(Rapisarda.et.al..1999,.2002)..Copper,.as.Cu(I),.can.then.
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