Identification of Histone H3 and H4 Amino Acid Residues Important for the Regulation of Arsenite Stress Signaling in Saccharomyces cerevisiae

Mutations in histones dysregulate copper homeostasis leading to defect in Sec61-dependent protein translocation mechanism in Saccharomyces cerevisiae

The translocation of proteins from the cytoplasm to the endoplasmic reticulum occurs via a conserved Sec61 protein channel. Previously, we reported that mutations in histones cause downregulation of a CUP1 copper metallothionein, and copper exposure inhibits the activity of Sec61. However, the role of epigenetic dysregulation on the activity of channel is not clear. Identification of cellular factors regulating copper metabolism and Sec61 activity is needed as the dysregulation can cause human diseases. In this study, we elucidate the intricate relationship between copper homeostasis and Sec61-mediated protein translocation. Utilizing copper-sensitive yeast histone mutants exhibiting deficiencies in the expression of CUP1, we uncover a copper-specific impairment of the protein translocation process, causing a reduction in the maturation of secretory proteins. Our findings highlight the inhibitory effect of copper on both cotranslational and posttranslational protein translocations. We demonstrate that supplementation with a copper-specific chelator or amino acids such as cysteine, histidine, and reduced glutathione, zinc, and overexpression of CUP1 restores the translocation process and growth. This study, for the first time provides a functional insight on epigenetic and metabolic regulation of copper homeostasis in governing Sec61-dependent protein translocation process and may be useful to understand human disorders of copper metabolism.

Biosorption of arsenite (As[III]) using Saccharomyces cerevisiae SRCM 501804 isolated from Korean turbid rice wine

The potentiality of Saccharomyces cerevisiae SRCM 501804 to remove arsenite (As[III]) in an aqueous solution was investigated in this study. The S. cerevisiae SRCM 501804 was isolated from Korean turbid rice wine (Makgeolli). The S. cerevisiae SRCM 501804 was characterized by phylogenetic analysis, Fourier transform infrared (FT-IR) spectroscopy, visual minerals technologies (MINTEQ) model, and point of zero charge (pH_pzc). The relationship between the factors (pH, biosorbent dosage, contact time, and concentration) and biosorption capacity was investigated. The S. cerevisiae SRCM 501804 was removed 31.1-90.1% of the As(III) depending on the initial biomass dosage within 1 h. Co-existing anions in aqueous solution showed a negative influence on the biosorption performance of As(III) in the order Cl^- > NO₃^- > SO₄^2- > CO₃^2-. The results of isotherms and kinetics suggested the Langmuir (R² > 0.95) and Pseudo-second order (R² > 0.99) models fit well with the equilibrium experimental data. The maximum biosorption capacity (q_m) of S. cerevisiae SRCM 501804 biomass for As(III) was found to be 113.9 mg/g from Langmuir isotherm. Based on the results, it can be concluded that the biomass of S. cerevisiae SRCM 501804 could be used as an effective bio-sorbent for As(III) biosorption in an aqueous solution.

Substitution of histone H3 arginine 72 to alanine leads to deregulation of isoleucine biosynthesis in budding yeast Saccharomyces cerevisiae

Histone residues play an essential role in the regulation of various biological processes. In the present study, we have utilized the H3/H4 histone mutant library to probe functional aspects of histone residues in amino acid biosynthesis. We found that histone residue H3R72 plays a crucial role in the regulation of isoleucine biosynthesis. Substitution of arginine residue (H3R72) of histone H3 to alanine (H3R72A) renders yeast cells unable to grow in the minimal media. Histone mutant H3R72A requires the external supplementation of either isoleucine, serine, or threonine for the growth in minimal media. We also observed that H3R72 residue and leucine amino acid in synthetic complete media might play a crucial role in determining the intake of isoleucine and threonine in yeast. Further, gene deletion analysis of ILV1 and CHA1 in H3R72A mutant confirmed that isoleucine is the sole requirement for growth in minimal medium. Altogether, we have identified that histone H3R72 residue may be crucial for yeast growth in the minimal medium by regulating isoleucine biosynthesis through the Ilv1 enzyme in budding yeast Saccharomyces cerevisiae.

Arsenic intoxication: general aspects and chelating agents

Arsenic (As) is widely used in the modern industry, especially in the production of pesticides, herbicides, wood preservatives, and semiconductors. The sources of As such as contaminated water, air, soil, but also food, can cause serious human diseases. The complex mechanism of As toxicity in the human body is associated with the generation of free radicals and the induction of oxidative damage in the cell. One effective strategy in reducing the toxic effects of As is the usage of chelating agents, which provide the formation of inert chelator–metal complexes with their further excretion from the body. This review discusses different aspects of the use of metal chelators, alone or in combination, in the treatment of As poisoning. Consideration is given to the therapeutic effect of thiol chelators such as meso-2,3-dimercaptosuccinic acid, sodium 2,3-dimercapto-1-propanesulfonate, 2,3-dimercaptopropanol, penicillamine, ethylenediaminetetraacetic acid, and other recent agents against As toxicity. The review also considers the possible role of flavonoids, trace elements, and herbal drugs as promising natural chelating and detoxifying agents.