Browsing by Subject "Metal homeostasis"

Mechanisms of copper homeostasis are of great interest partly due to their connection to debilitating genetic and neurological disorders. The family of high-affinity copper transporters (Ctr) is responsible for extracellular copper acquisition and internalization in yeast, plants, and mammals, including human. The extracellular domain of the human high-affinity copper transporter (hCtr1) contains essential Cu-binding methionine-rich MXXM and MXM (Mets) motifs that are important for copper acquisition and transport. The hCtr1 extracellular domain also contains potential copper binding histidine (His) clusters, including a high-affinity Cu(II) ATCUN site. As of yet, extracellular His clusters have no established significance for hCtr1 function. We have made model peptides based on the extracellular copper acquisition domain of hCtr1 that is rich in His residues and Mets motifs. The peptides' Cu(I) and Cu(II) binding properties have been characterized by UV-Vis and mass spectrometry. Our findings have been extended to a mouse cell model and we show that His residues are important for hCtr1 function likely because of their contribution to strong copper-binding sites in the hCtr1 extracellular domain responsible for copper acquisition.

Copper's pro-oxidant property is also medicinally promising if it can be harnessed to induce oxidative stress as a cancer chemotherapy strategy. Our lab has designed a photocleavable caged copper complex that can selectively release redox-active copper in response to light. The thermodynamic copper binding properties of these potential chemotherapeutics have been characterized

Maintenance of metal homeostasis is critical to cell survival due to the multitude of cellular processes that depend on one or more metal cofactors. We show that the opportunistic fungal pathogen Candida albicans becomes sensitized to both Cu limitation and Cu elevation during exposure in liquid culture to the antifungal drug fluconazole, a widely prescribed antifungal agent. Cu supplementation reduces tolerance of C. albicans to fluconazole in a way that does not require formation of a Cu–fluconazole complex. Rather, our data point to a less obvious relationship between drug stress and Cu availability that gives rise to metal-mediated outcomes of drug treatment. qRT-PCR, EPR, fluorescence, and ICP-MS studies demonstrate that C. albicans extensively remodels its metal homeostasis networks to respond to treatment with fluconazole. These adaptation strategies include increased Cu import and storage, increased retention of Fe, Mn, and Zn, altered utilization of Cu- and Mn-dependent enzymes, mobilization of intracellular Fe stores, and increased production of the heme prosthetic group utilized by the enzyme target of fluconazole. Furthermore, RNA-seq analysis reveals that co-treatment with fluconazole and Cu gives rise to unique patterns of gene expression that illustrate the profound impacts of small fluctuations in Cu availability on the transcriptomic response to fluconazole stress. Finally, we show that fluconazole causes substantial changes to the metalloproteome of C. albicans, most notably to the levels of Cu proteins. The findings offer a new perspective for thinking about fungal response to drug stress that pushes cells out of their metal homeostatic zones, leading them to enact metal-associated adaptation mechanisms to restore homeostasis to survive.