Overexpression of the Saccharomyces cerevisiae magnesium transport system confers resistance to aluminum ion
Overexpression of the Saccharomyces cerevisiae magnesium transport system confers resistance to aluminum ion
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DOI：
10.1074/jbc.273.3.1727
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发表时间：
1998-01-16
影响因子：
4.8
通讯作者：
Gardner, RC
中科院分区：
文献类型：
--
作者：
MacDiarmid, CW;Gardner, RC
离子铝(Al3+)对植物、微生物、鱼类和动物都有毒性，但其毒性机制尚不清楚。我们分离到了两个酵母基因(ALR1和ALR2)，它们在过量表达时提高了对Al3+和GA3+离子的耐受性，同时提高了菌株对锌、锰、镍、铜、钙和La3+离子的敏感性。Air蛋白与鼠伤寒沙门氏菌Cora蛋白同源，鼠伤寒沙门氏菌Cora蛋白是一种位于细菌周质膜上的镁和Co2+运输系统。缺乏ALR基因活性的酵母菌株需要额外的镁离子才能生长，ALR1或ALR2的表达纠正了需要镁离子的表型。结果表明，ALR基因编码酵母对镁和其他二价阳离子的吸收系统，这一假设得到了ALR高表达菌株Co-57(2+)积累增加和ALR表达缺失菌株Co-57(2+)积累减少的证据的支持。ALR的过表达也克服了Al3+离子对Co2+吸收的抑制。结果表明，铝对酵母菌的毒性是由于空气蛋白中镁离子内流减少所致。酵母镁离子转运系统的分子鉴定有助于更好地理解真核细胞中镁离子稳态的调控。
Ionic aluminum (Al3+) is toxic to plants, microbes, fish, and animals, but the mechanism of its toxicity is unknown. We describe the isolation of two yeast genes (ALR1 and ALR2) which confer increased tolerance to Al3+ and Ga3+ ions when overexpressed while increasing strain sensitivity to Zn2+, Mn2+, Ni2+, Cu2+, Ca2+, and La3+ ions, The Air proteins are homologous to the Salmonella typhimurium CorA protein, a bacterial Mg2+ and Co2+ transport system located in the periplasmic membrane. Yeast strains lacking ALR gene activity required additional Mg2+ for growth, and expression of either ALR1 or ALR2 corrected the Mg2+-requiring phenotype. The results suggest that the ALR genes encode the yeast uptake system for Mg2+ and other divalent cations, This hypothesis was supported by evidence that Co-57(2+) accumulation was elevated in ALR-overexpressing strains and reduced in strains lacking ALR expression. ALR overexpression also overcame the inhibition of Co2+ uptake by Al3+ ions. The results indicate that aluminum toxicity to yeast occurs as a consequence of reduced Mg2+ influx via the Air proteins. The molecular identification of the yeast Mg2+ transport system should lead to a better understanding of the regulation of Mg2+ homeostasis in eukaryote cells.