Compounds affecting membranes that inhibit protein synthesis in yeast

The regulation of protein synthesis is a central process in cellular function. Prior research has shown that ionic gradients across membranes influence translation in various organisms. However, the specific role of membrane-permeabilizing compounds in yeast protein synthesis remains unclear. Established knowledge includes the general understanding that ionophores disrupt membrane potentials. This paper addresses a gap in how these disruptions affect translation in fungal cells. No prior work had resolved whether ionophores inhibit translation initiation or elongation in yeast. This uncertainty drove the investigation into amphotericin B and related compounds. The study builds on earlier findings about ionophore effects in mammalian cells. It explores whether similar mechanisms apply to yeast. The research aims to clarify the molecular targets of these inhibitors.

The purpose of the study is to determine how ionophores and other membrane-affecting compounds inhibit protein synthesis in yeast. The researchers aim to identify the specific stage of translation affected by these compounds. They investigate whether changes in intracellular potassium levels are responsible for the observed inhibition. The study seeks to compare the effects of amphotericin B with other ionophores like nystatin and gramicidin D. It also examines whether these effects are unique to yeast or shared with bacteria like E. coli. The goal is to clarify the mechanism of inhibition at the polysomal level. The study evaluates whether the observed effects are due to membrane permeabilization or other factors. The researchers aim to establish a link between ionic changes and translation suppression.

The study uses ionophores and membrane-active compounds to treat yeast cells and assess their effects on protein synthesis. Researchers measure the protein-synthesizing activity in treated cells using labeled amino acids and nucleosides. They analyze polysomal profiles in yeast spheroplasts to determine the stage of translation affected. The study compares the effects of amphotericin B with compounds like nystatin and gramicidin D. It evaluates the impact of these compounds on both protein and ribonucleic acid synthesis. The researchers assess whether labeled amino acid transport is affected at the concentrations used. They investigate the role of potassium concentration in reversing the inhibition. The study includes experiments on E. coli and Staphylococcus aureus for comparative analysis.

Amphotericin B strongly inhibits protein and RNA synthesis in yeast cells without affecting amino acid transport. The compound alters polysomal profiles, suggesting that translation initiation is the primary target. Nystatin and other ionophores also inhibit protein synthesis in yeast and mammalian cells. Increasing potassium concentration in the medium partially reverses the inhibition by amphotericin B. The effects of gramicidin D, nigericin, and monensin are consistent across different cell types. The study shows that the inhibition is not due to precursor transport but to cytoplasmic ionic changes. Amphotericin B affects yeast ribosomes more than other cell types. The findings suggest that cytoplasmic potassium levels are linked to translation suppression.

The study concludes that amphotericin B inhibits translation in yeast by targeting initiation. The effects are not due to precursor transport but to changes in intracellular potassium levels. The findings suggest that membrane-permeabilizing compounds disrupt translation through cytoplasmic ionic changes. The study supports the hypothesis that ionic gradients are essential for translation in yeast. The results align with prior observations in mammalian cells regarding ionophore effects. The researchers propose that cytoplasmic potassium concentration is a key factor in translation regulation. The study does not claim that these compounds are essential for all translation processes. The findings may suggest that ionic regulation is a conserved mechanism across species.