| Abstrakt: |
Saccharomyces cerevisiaeis by far the best‐studied unicellular eukaryote. Although yeast cells are very similar to higher eukaryotes in many respects, there is striking evidence that S. cerevisiaeis not a perfect model for a eukaryotic cell (cf. 1). Here we report that yeast proteins contain a significantly lower amount of cysteine residues compared to other eukaryotes. Explanations for this phenomenon could not be found in the sulfur metabolism of yeast, which showed no major differences from other organisms (2–4). However, previous examinations could link a defect in sulfate uptake of S. cerevisiaeto an increased resistance against toxic substances like selenate and chromate in the environment, which share the same permeases (5–7). This environmental problem might have caused S. cerevisiaeto down‐regulate its sulfate uptake and therefore lead to a lower amount of available sulfur in the cell, making it necessary to replace all dispensable sulfur amino acids in proteins. We show in two examples that S. cerevisiaeproteins contain only such cysteine residues that are structurally or functionally needed. Therefore, we conclude that S. cerevisiaehas solved a widespread environmental problem in a specific way which might be unique among eukaryotes.—Scheibel, T., Bell, S., Walke, S. S. cerevisiaeand sulfur: a unique way to deal with the environment. FASEB J.11, 917–921 (1997) |
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