Diapositiva 1

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• The average adult male contains only 100 mg of
  Cu.
• Cu1 prefers sulfur donor ligands (cysteine or
  methionine), whereas Cu2 prefers nitrogen donors
  (histidine) or oxygen donors (glutamate or
  aspartate).
• Although more than 90 of the serum Cu is bound
  by ceruloplasmin, mice lacking ceruloplasmin have
  no apparent defect in Cu absorption or
  distribution.
• alterations in Cu balance have been linked, but
  not causally associated, to changes in senile
  plaque deposition in Alzheimers disease.
• Cu binding to a-synuclein has been linked to the
  aggregation of this protein, which is observed in
  Parkinsons disease.
• N-terminal octapeptide repeats in the prion
  protein (PrP) serves as high-affinity Cu2
  binding sites that may alter the structure of PrP
  to a form associated with prion disease

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Examples of Cu binding and Cu homeostasis
proteins Amyloid precursor protein (APP) Protein
involved in neuronal development and potentially
Cu metabolism (Alzheimers disease) Atox1
Metallochaperone that delivers Cu to ATP7A and
ATP7B Cu1 transporters ATP7A Cu1-transporting
P-type ATPase expressed in all tissues except
liver ATP7B Cu1-transporting P-type ATPase
expressed primarily in the liver Carbon monoxide
dehydrogenase to acetyl-CoA synthase Moorella
thermoacetica reduces CO2 to CO and assembly of
acetyl-CoA Ceruloplasmin Serum ferroxidase that
functions in Fe3 loading onto transferrin Coagula
tion factors V and VIII Homologous pro-coagulants
present on the surface of platelets (blood
coagulation). CCS Metallochaperone that delivers
Cu to Cu/Zn SOD CopZ Archaeoglobus fulgidus
2Fe-2S and Zn2-containing Cu chaperone Cox17
Metallochaperone that transfers Cu to Sco1 and
Cox11 for cytochrome oxidase Cu loading in
mitochondria Ctr1 High-affinity Cu1 transporter
involved in cellular Cu uptake Cu/Zn SOD (SOD1)
Antioxidant enzyme Cytochrome c oxidase
mitochondrial respiratory chain. Dopamine
â-hydroxylase (DBH) Oxygenase, converts dopamine
to norepinephrine
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Ethylene receptor (ETR1) Member of a plant
receptor family that uses a Cu cofactor for
ethylene binding and signaling Hemocyanin Oxygen
transport in invertebrates Hephaestin
Transmembrane multi-Cu ferroxidase iron efflux
from enterocytes and macrophages Glucose oxidase
Pentose phosphate pathway oxidoreductase that
catalyzes the oxidation of D-glucose into
D-glucono-1, 5-lactone and hydrogen
peroxide Laccase Phenol oxidase involved in
melanin production Lysyl oxidase Catalyzes
formation of aldehydes from lysine in collagen
and elastin precursors for connective tissue
maturation Metallothionein Cysteine-rich
small-molecular-weight metal-binding and
detoxification protein Peptidylglycine-a-amidating
mono-oxygenase (PAM) conversion of
peptidylglycine substrates into a-amidated
products neuropeptide maturation Prion protein
(PrP) Protein whose function is unclear but binds
Cu via the N-terminal octapeptide repeats Steap
proteins/Fre1/Fre2 Family of metalloreductases
for Fe3 and Cu2 reduction Tyrosinase Monophenol
mono-oxygenase melanin synthesis XIAP Inhibitor
of apoptosis through binding and catalytic
inhibition of several caspases
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(No Transcript)
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Defects in Cu homeostasis are directly
responsible for human diseases. Mutations in the
ATP7A or ATP7B genes, encoding P-type
Cu1-transporting ATPase pumps expressed in
extrahepatic tissues or in the liver,
respectively, cause Menkes and Wilsons
diseases. Menkes disease (ATP7A) is an X-linked
lethal disorder of intestinal Cu
hyperaccumulation with severe Cu deficiency in
peripheral tissues and concomitant deficits in
Cu-dependent enzymes that lead to the clinical
hallmarks of the disease. Wilsons disease
(ATP7B) is an autosomal recessive disease
characterized by striking hepatic and neuronal Cu
overload, hepatotoxicity, neuropsychological and
other defects that require chronic therapy to
enhance Cu excretion or reduce Cu absorption.
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• Assorbimento del rame

Ligandi???
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Struttura di Ctr-1
(?)
Facilita la cattura e lendocitosi di Crt-1 a
basse concentrazioni di rame
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Cu import, intracellular routing and biliary
secretion in the liver. Cu1 is imported at the
plasma membrane by Ctr1 and routed to Cu/Zn SOD1
by CCS (Cu chaperone for SOD), to the ATP7B
(Cu1-transporting P-type ATPase) at the
secretory apparatus, and at the bile canalicular
membrane by Atox1. Cu movement to the
mitochondria may involve one or more as-yet
uncharacterized intracellular ligands (denoted L)
(COX-17 ?).
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In the intermembrane space (IMS), Cu1 is bound
by Cox17 and delivered either to Sco1, which
transfers the Cu to the Cox2 subunit, or to
Cox11, which delivers Cu to the Cox1 subunit of
cytochrome oxidase (CCO). A novel Cu ligand
(L) has been isolated from both yeast and mouse
liver and may function in mitochondrial Cu
delivery
COX17
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(Cu chaperone)
Cu1 delivery pathway to ATP7B that pumps excess
Cu1 into the bile for excretion. Mutation of
ATP7B causes Wilsons disease, which is
characterized by a Cu overload in the liver,
neurons and other tissues. A series of ligand
exchange reactions between Atox1 and the metal
binding motifs of ATP7B (CxxC) results in the
movement of Cu1 from Atox1 to ATP7B, followed by
transport across the hepatocyte membrane into the
bile. Similar Atox1 and ATP7A for Cu1 movement
across the basolateral membrane of IECs, and
Atox1 and ATP7A or ATP7B for Cu1 incorporation
into secreted Cu-dependent proteins.
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The CCS domain II structurally resembles Cu/Zn
SOD and facilitates many of the CCS-SOD1
interactions. Domains I and III have CX2C and CXC
Cu1 binding domains. Heterodimerization between
a monomer of Cu1-loaded CCS and Zn-loaded SOD1
results in the transfer of Cu onto SOD1 in a
process that involves oxygen-dependent
intrasubunit disulfide bond formation in SOD1
catalyzed by Cu-CCS. The transient accumulation
of Cu1-loaded CCS, when all SOD1 is
Cu-metallated, could expose a lysine residue for
ubiquitination.
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Human pathogen C. neoformans. Extracellular Cu,
most likely reduced by the Fre family of
metalloreductases, is transported into the cell
as Cu1 through the high-affinity Ctr4
transporter. The cytosolic Cu chaperone Atx1
delivers Cu to the secretory compartment via the
P-type ATPase Ccc2, where it becomes incorporated
into Cu-dependent enzymes including the
multi-Cu ferroxidase Fet3 that, together with the
Ftr1 permease, mediate high affinity iron uptake,
and into laccase.
Ctr4
Fre
Ftr1
Fre
Cuf1
The Cuf1 transcription factor regulates the
expression of cellular Cu homeostasis genes.
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Many questions remain to be answered with respect
to Cu homeostasis. How do Cu chaperones obtain
Cu, and is this process prioritized depending on
the physiological state of cells? Can new
Cu-dependent proteins be identified, and will
they add to the diversity of functions already
known for Cu in biology? How is the import of Cu
coordinated with its mobilization from
intracellular stores? What is the chemical nature
of Cu ligands that ferry Cu around cells and
throughout the bloodstream or across the blood
brain barrier? How do cells sense when a protein
is Cu-loaded and appropriately regulate protein
steady state levels or subcellular trafficking?
Can sensitive and high-resolution techniques be
developed for the subcellular localization,
quantitation and speciation of Cu? Can Cu ligands
and delivery mechanisms be developed to treat
diseases such as Menkes disease? Is Cu causally
related to neurodegenerative diseases such as
Alzheimers, Parkinsons and prion disease, and
if so, how can manipulation of bioavailable Cu
alter the outcome of these diseases? Further
investigations of the fundamental biochemistry,
genetics, cell biology, physiology and chemistry
of Cu will be critical to answering these
questions that explore the roles of Cu in health
and disease.