Manganese accumulation in yeast cells |
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Authors: | Francesca Galiazzo Jens Zacho Pedersen Patrizia Civitareale Alma Schiesser Giuseppe Rotilio |
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Institution: | (1) Department of Biology, Tor Vergata University of Rome and Consiglio Nazionale delle Ricerche Center for Molecular Biology, Tor Vergata University, Via O. Raimondo, I-00173 Rome, Italy;(2) Institute of Microbiology and Agricultural Technology, University of Tuscia, Viterbo, Italy |
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Abstract: | Summary Manganese accumulation was studied by room-temperature electron spin resonance (ESR) spectroscopy inSaccharomyces cerevisiae grown in the presence of increasing amounts of MnSO4. Mn2+ retention was nearly linear in intact cells for fractions related to both low-molecular-mass and macromolecular complexes (free and bound Mn2+, respectively). A deviation from linearity was observed in cell extracts between the control value and 0.1 mM Mn2+, indicating more efficient accumulation at low Mn2+ concentrations. The difference in slopes between the two straight lines describing Mn2+ retention at concentrations lower and higher than 0.1 mM, respectively, was quite large for the free Mn2+ fraction. Furthermore it was unaffected by subsequent dialyses of the extracts, showing stable retention in the form of low-molecular-mass complexes. In contrast, the slope of the line describing retention of bound Mn2+ at concentrations higher than 0.1 mM became less steep after subsequent dialyses of the cell extracts. This result indicates that the macromolecule-bound Mn2+ was essentially associated with particulate structures. In contrast to Cu2+, Mn2+ had no effect on the major enzyme activities involved in oxygen metabolism except for a slight increase of cyanide-resistant Mn-superoxide dismutase activity, due to dialyzable Mn2+ complexes. |
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Keywords: | Manganese Electron spin resonance Superoxide dismutase Saccharomyces cerevisiae Yeast |
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