Intracellular copper storage and delivery in a bacterium

A family of cytosolic copper (Cu) storage proteins (the Csps) are widespread in bacteria. The Csps can bind large quantities of Cu(I) via their Cys-lined four-helix bundles, and the majority are cytosolic (Csp3s). This is inconsistent with the current dogma that bacteria, unlike eukaryotes, have evolved not to maintain intracellular pools of Cu due to its potential toxicity. Sporulation in Bacillus subtilis has been used to investigate if a Csp3 can store Cu(I) in the cytosol for a target enzyme. The activity of the Cu-requiring endospore multi-Cu oxidase BsCotA (a laccase) increases under Cu-replete conditions in wild type B. subtilis, but not in the strain lacking BsCsp3. Cuprous ions readily transfer from BsCsp3, but not from the cytosolic copper metallochaperone BsCopZ, to BsCotA in vitro producing active enzyme. Both BsCsp3 and BsCotA are upregulated during late sporulation. The hypothesis we propose is that BsCsp3 acquires and stores Cu(I) in the cytosol for BsCotA.

COMMD1 Exemplifies the Power of Inbred Dogs to Dissect Genetic Causes of Rare Copper-Related Disorders

Wilson’s Disease is a rare autosomal recessive disorder in humans, often presenting with hepatic copper overload. Finding the genetic cause of a rare disease, especially if it is related to food constituents like the trace element copper, is a Herculean task. This review describes examples of how the unique population structure of in-bred dog strains led to the discovery of a novel gene and two modifier genes involved in inherited copper toxicosis. COMMD1, after the discovery in 2002, was shown to be a highly promiscuous protein involved in copper transport, protein trafficking/degradation, regulation of virus replication, and inflammation. Mutations in the ATP7A and ATP7B proteins in Labrador retrievers and Dobermann dogs resulted in a wide variation in hepatic copper levels in these breeds. To our knowledge, numerous dog breeds with inherited copper toxicosis of unknown genetic origin exist. Therefore, the possibility that men’s best friend will provide new leads in rare copper storage diseases seems realistic.

Wilson Disease in Children: Diagnosis and Management Update

Wilson disease is an autosomal recessive, copper storage disease, caused by a mutation in the ATP7B gene. Due to mutation in ATP7B is decreased secretion of ceruloplasmin into blood and decrease in excretion of copper into bile. Excess copper accumulate to toxic levels,mainly in the liver and secondarily in other organs. Children clinically become symptomatic after the age of 5 years. Clinical features ranges from asymptomatic raised transaminases to variable degree of liver disease, neurological symptoms and according involvement of other oragns. Diagnosis of Wilson disease is challenging. Modified Leip-zig score is useful for diagnosis. Treatment can be done with zinc and other chelators. KYAMC Journal Vol. 11, No.-4, January 2021, Page 212-217

COPPER AND IRON SUPPLEMENTATION IN THE TROPICAL ENVIRONMENT EFFECTS ON HAEMATOLOGICAL MEASUREMENTS, ORGAN WEIGHTS, TISSUE COPPER AND IRON

The study which lasted 3 months was a factorial arrangement in which nine dietary treatments resulting from supplementation of a commercial layers diet with 0, 200 or 400 mg/kg Copper and 0, 100 or 200 mg/kg Iron were fed to 135 fifty two-week old laying hens of the Golden Hubbard Connect Strain. After 12 weeks on the diets, three birds, randomly selected from each treatment, were slaughtered and their blood, liver, spleen and heart analysed for effect of supplementary copper and iron on haemoglobin content, packed cell volume and weights of the liver, spleen and heart and their copper and iron concentrations. No significant effects of supplementary copper or Iron or their interaction were observed on haemoglobin, packed cell volume or weights of the liver, spleen and heart. However, dietary iron supplementation produced significant (P<0.05) effects on iron storage in the liver and spleen but not on copper storage. On the other hand, copper addition significantly (P<0.05) increased liver storage of copper and spleen storage of iron. Supplementary copper and iron Interaction effects which were not significant for all other measurements, were observed to be significant (P<0.05) for liver copper and Iron concentrations and spleen copper concentration and highly significant (P<0.01) for spleen iron concentration.

Copper Supplementation, A Challenge in Cattle

Ensuring adequate copper supplementation in ruminants is a challenging task due to the complexity of copper metabolism in these animals. The three-way interaction between copper, molybdenum and sulphur (Cu-Mo-S) in the rumen makes ruminants, particularly cattle, very susceptible to suffering from secondary copper deficiency. Paradoxically, excessive copper storage in the liver to prevent deficiency becomes a hazard when ruminants are fed copper-supplemented diets even slightly above requirements. While cattle were traditionally thought to be relatively tolerant of copper accumulation, and reports of copper poisoning were until recently somewhat rare, in recent years an increased number of episodes/outbreaks of copper toxicity in cattle, particularly in dairy cattle, have been reported worldwide. The growing number of lethal cases reported seems to indicate that copper intoxication is spreading silently in dairy herds, urging the development of strategies to monitor herd copper status and improve farmers’ awareness of copper toxicity. In fact, monitoring studies carried out on numerous samples collected from culled animals in slaughterhouses and/or diagnostic laboratories have demonstrated that large numbers of animals have hepatic copper concentrations well above adequate levels in many different countries. These trends are undoubtedly due to copper supplementation aimed at preventing copper deficiency, as dietary copper intake from pasture alone is unlikely to cause such high levels of accumulation in liver tissue. The reasons behind the copper overfeeding in cattle are related both to a poor understanding of copper metabolism and the theory of “if adding a little produces a response, then adding a lot will produce a better response”. Contrary to most trace elements, copper in ruminants has narrow margins of safety, which must also be formulated considering the concentrations of copper antagonists in the diet. This review paper aims to provide nutritionists/veterinary practitioners with the key points about copper metabolism in cattle to guarantee an adequate copper supply while preventing excessive hepatic copper loading, which requires à la carte copper supplementation for each herd.

Acquisition of ionic copper by a bacterial outer membrane protein

Copper, while toxic in excess, is an essential micronutrient in all kingdoms of life due to its essential role in the structure and function of many proteins. Proteins mediating ionic copper import are known in eukaryotes, but have not yet been described in prokaryotes. Here we show that Pseudomonas aeruginosa OprC is a TonB-dependent transporter that mediates acquisition of ionic copper. Crystal structures of wild type and mutant OprC variants with silver and copper, as well as ICP-MS and electron paramagnetic resonance (EPR), suggest that binding of Cu(I) occurs via a surface-exposed methionine track leading towards an unprecedented CxxxM-HxM metal binding site that binds Cu(I) directly and can facilitate reduction of Cu(II) via the cysteine thiol. Together with quantitative proteomics and growth assays, our data identify OprC as an abundant component of bacterial copper biology that enables copper acquisition and potentially copper storage under a wide range of environmental conditions.

The oxygen reactivity of an artificial hydrogenase designed in a reengineered copper storage protein

The O2 reactivity of an artificial biomolecular hydrogenase, the nickel binding protein (NBP) is investigated.