Mutations eliminating the protein export function of a membrane-spanning sequence.
Mutations eliminating the protein export function of a membrane-spanning sequence.
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DOI：
10.1016/s0021-9258(19)61980-0
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发表时间：
1994-11
期刊：
影响因子：
--
通讯作者：
E. Lee;C. Manoil
中科院分区：
文献类型：
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作者：
E. Lee;C. Manoil
单个膜蛋白跨区序列可以促进蛋白质输出。为了帮助定义这一作用所需的序列特征，我们确定了由大肠杆菌丝氨酸化学受体的第一个生成序列(TM1)介导的中断输出的突变。利用β-半乳糖苷酶和碱性磷酸酶基因融合产生突变的跨越序列，并对其进行鉴定。TM1的蛋白质输出功能对单电荷残基有明显的耐受性，需要引入成对的带电氨基酸来消除输出。结果符合一个模型，在该模型中，出口需要一系列疏水性总和超过特定阈值的未带电残基。该阈值接近可切割信号序列功能所需的最小疏水性。此外，在一组具有拓扑学特征的膜蛋白中，阈值接近观察到的野生型跨越序列的最小疏水性。
Individual membrane protein spanning sequences can promote protein export. To help define the sequence features necessary for this action, we identified mutations disrupting export mediated by the first spanning sequence (TM1) of the Escherichia coli serine chemoreceptor. Mutant spanning sequences were generated and characterized using beta-galactosidase and alkaline phosphatase gene fusions. The protein export function of TM1 was remarkably tolerant of single charged residues, and the introduction of pairs of charged amino acids was necessary to eliminate export. The results are accommodated by a model in which export requires a stretch of uncharged residues whose summed hydrophobicity exceeds a particular threshold value. This threshold approximates the minimum hydrophobicity required for cleavable signal sequence function. In addition, the threshold was near the minimum hydrophobicity observed for wild-type spanning sequences in a collection of topologically characterized membrane proteins.