One of three transmembrane stretches is sufficient for the functioning of the SecE protein, a membrane component of the E. coli secretion machinery.
One of three transmembrane stretches is sufficient for the functioning of the SecE protein, a membrane component of the E. coli secretion machinery.
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三个跨膜延伸之一足以发挥 SecE 蛋白（大肠杆菌分泌机制的膜成分）的功能。
DOI：
10.1002/j.1460-2075.1991.tb07699.x
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Beckwith,J
中科院分区：
文献类型：
--
作者：
Schatz,PJ;Bieker,KL;Ottemann,KM;Silhavy,TJ;Beckwith,J
大肠杆菌 secE (prlG) 基因编码完整的细胞质膜蛋白，该蛋白是细胞分泌机制的一部分。几乎整个基因的缺失使细胞依赖于互补的 secE+ 质粒的存在，表明 SecE 蛋白对于生长至关重要。删除羧基末端序列或大量靠近 SecE 氨基末端的删除仍然可以补充致死性删除。这一缺失分析表明 SecE 蛋白的基本结构域仅包含其三个疏水性跨膜片段中的一个。三个显性 prlG 信号序列抑制因子中的两个映射到该片段。与 SecE 对主要结构变化不敏感一致，一些冷敏感突变导致致死性不是因为蛋白质发生任何变化，而是因为其表达水平降低。我们的结果表明，在较低的温度下需要较高水平的蛋白质。这些发现是根据分泌机制各个组成部分之间的相互作用进行讨论的。
The E. coli secE (prlG) gene codes for an integral cytoplasmic membrane protein which is part of the cell's secretory machinery. A deletion of nearly the entire gene renders the cell dependent on the presence of a complementing secE+ plasmid, indicating that the SecE protein is essential for growth. Deletions which remove carboxy‐terminal sequences or substantial amounts near the amino‐terminus of SecE can still complement the lethal deletion. This deletion analysis suggests that the essential domain of the SecE protein includes only a single one of its three hydrophobic membrane‐spanning segments. Two of three dominant prlG signal sequence suppressors map to this segment. Consistent with the insensitivity of SecE to major structural changes, several cold‐sensitive mutations cause lethality not because of any change in the protein, but because of a reduction in its level of expression. Our results suggest that higher levels of the protein are needed at the lower temperature. These findings are discussed in terms of the interactions between various components of the secretory machinery.