Handling Copper: A Paradigm for the Mechanisms of Metal Ion Homeostasis - Environmental Contamination: Health Risks and Ecological Restoration - page 277

TABLE 13.3
List.of.Copper.Traficking.Proteins.in.Photosynthetic.Cyanobacteria

CopperTransport-
RelatedProteins

Cellular
Location Function Homologs References

Cyanobacteria
Synechocystis
Copper.Import
FutA1
FutA2

Periplasm
Periplasm

Aids.in.Cu.import
Aids.in.Cu.import

Katoh.et.al..
(2001a,b),.
Waldron.
et.al..(2007)

P-type.ATPase.
Transporters
CtaA

Plasma.
membrane

Cu(I).inlux PAA1.

( A. thaliana )

Phung.et.al..
(1994)

PacS Thylakoid.

membrane

Cu(I).inlux PAA2.

( A. thaliana )

Kanamaru.
et.al..(1994)

Cu.Metallochaperones
Atx1

Cytoplasm Transports.Cu(I).

from.cell.
membrane.to.
thylakoid.
membrane

Atx1.
( S. cerevisae )
Atx1.
( A. thaliana )
CCH.
( A. thaliana )

Tottey.et.al..
(2002)

Targets.for.Cu(I)
PC.(Plastocyanin)

Thylakoid Electron.transport.

in.photosynthesis

CO.(Cytochrome.
oxidase)

Thylakoid Electron.transport.

in.respiration

copper.concentrations;.however,.CopB.mutants.show.signiicantly.increased.
cellular.copper.levels. (Odermatt.et.al..1994)..This.suggests.that.CopA.is.an.
ion. importer,. while. CopB. functions. as. an. eflux. mechanism.. Intracellular.
levels. of. copper. are. regulated. by. a. cop . operon. that. consists. of. four. genes:.
copA ,. copB ,. copY ,. copZ ..The.genes. copA .and. copB .encode.the.two.copper.trans-
porters,. while. copY . acts. as. a. repressor. and. copZ . functions. as. an. activator.
(Odermatt.and.Solioz.1995)..Although.currently.unknown,.it.is.thought.that.
Enterococcus hirae .contains.an.extracellular.reductase.to.convert.Cu(II).to.Cu(I).
for.cellular.uptake.of.copper..Once.copper.enters.the.cell.through.the.CopA.
transporter,.a.copper.chaperone.called.CopZ.shuttles.Cu(I).to.CopY,.a.tran-
scriptional.repressor.(Odermatt.and.Solioz.1995,.Strausak.and.Solioz.1997)..
The. current. model. for. copper. regulation. can. be. summarized. as. follows:.
when.zinc.is.bound.to.CopY.it.represses.transcription.of.the. cop .operon;.how-
ever,.if.CopZ.delivers.copper.to.CopY,.the.repressor.disassociates.from.the.
promoter.allowing.transcription.to.occur.(Cobine.et.al..1999,.Magnani.and.