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首页> 外文期刊>Journal of bacteriology >Synthesis and Differential Turnover of the CYS3 Regulatory Protein of Neurospora crassa Are Subject to Sulfur Control
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Synthesis and Differential Turnover of the CYS3 Regulatory Protein of Neurospora crassa Are Subject to Sulfur Control

机译：粗糙神经孢菌CYS3调节蛋白的合成和差异化周转受硫控制

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摘要

The transcription factor CYS3 of Neurospora crassa is a positive regulator of the sulfur regulatory circuit which contains many structural genes involved in sulfur metabolism. Expression and degradation of the CYS3 protein are precisely regulated in a sulfur-dependent manner. cys-3 expression was found to be fully repressed by high concentrations of methionine or inorganic sulfate present in the culture medium and to be derepressed when these favored sulfur sources were limited. cys-3 transcripts could be readily detected within 2 h after derepression, whereas the CYS3 protein was not found until after 4 h. CYS3 is stable, with a half-life greater than 4 h under low-sulfur conditions when it is required for cell growth. However, it is degraded relatively quickly when methionine or inorganic sulfate becomes available. Upon sulfur repression, cys-3 transcripts disappeared within 30 min with an estimated half-life of 5 min whereas CYS3 protein almost entirely disappeared in 1 h with a half-life of approximately 10 min. These results suggest that a selective elimination of CYS3 is a highly regulated process. Site-directed mutagenesis showed that Lys-105 of CYS3 is important for its instability. The change of this single residue from lysine to glutamine resulted in a prolonged half life of CYS3 and impaired responsiveness of CYS3 degradation to sulfur level changes.
机译：芥子神经孢菌的转录因子CYS3是硫调节回路的正调节子，它包含许多参与硫代谢的结构基因。 CYS3蛋白的表达和降解以硫依赖的方式精确调控。发现 cys-3 表达被培养基中存在的高浓度蛋氨酸或无机硫酸盐完全抑制，而当这些有利的硫源受到限制时，其表达会被抑制。解除抑制后2 h内即可检测到 cys-3 转录本，而直到4 h后才发现CYS3蛋白。 CYS3是稳定的，当细胞生长需要时，在低硫条件下半衰期大于4小时。但是，当可获得蛋氨酸或无机硫酸盐时，它的降解速度相对较快。抑制硫后， cys-3 转录本在30分钟内消失，估计半衰期为5分钟，而CYS3蛋白在1小时内几乎完全消失，半衰期约为10分钟。这些结果表明CYS3的选择性消除是一个高度监管的过程。定点诱变表明CYS3的Lys-105对于其不稳定性很重要。从赖氨酸到谷氨酰胺的单个残基的变化导致CYS3的半衰期延长，并且CYS3降解对硫水平变化的响应性受损。

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