SECD AND SECF FACILITATE PROTEIN EXPORT IN ESCHERICHIA-COLI
SECD AND SECF FACILITATE PROTEIN EXPORT IN ESCHERICHIA-COLI
复制标题
DOI：
10.1002/j.1460-2075.1994.tb06293.x
复制
发表时间：
1994-02-01
期刊：
影响因子：
11.4
通讯作者：
BECKWITH, J
中科院分区：
文献类型：
--
作者：
POGLIANO, JA;BECKWITH, J
我们在这里表明，在细菌大肠杆菌中的蛋白质易位率取决于SecD和SecF蛋白在细胞中的水平。SecD和SecF的过表达刺激野生型细胞中的易位并改善具有突变信号序列的蛋白质的输出。从细胞中消耗SecD和SecF大大减少但不消除蛋白质易位。A secDF.：编码两种蛋白质的基因缺失的kan无效突变体对生长和蛋白质输出是冷敏感的，在37 ℃下具有严重的输出缺陷，并且几乎不能存活。secD无效突变体和secF无效突变体的表型与secDF：：kan双无效突变体相同。这些结果部分解决了遗传研究和结果之间的冲突，在体外易位系统，不需要SecD和SecF的活动，肯定这些蛋白质的重要性，出口过程中，并建议SecD和SecF功能一起刺激蛋白质出口的作用从根本上不同于其他Sec蛋白质。我们的研究结果为蛋白质出口的早期步骤是冷敏感的这一概念提供了额外的支持。
We show here that the rate of protein translocation in the bacterium Escherichia coli depends on the levels of the SecD and SecF proteins in the cell. Overexpression of SecD and.SecF stimulates translocation in wild type cells and improves export of proteins with mutant signal sequences. Depletion of SecD and SecF from the cell greatly reduces but does not abolish protein translocation. A secDF.:kan null mutant deleted for the genes encoding both proteins is cold-sensitive for growth and protein export, has a severe export defect at 37-degrees-C and is barely viable. The phenotypes of a secD null mutant and a secF null mutant are identical to the secDF::kan double null mutant. These results partially resolve the conflict between genetic studies and results from in vitro translocation systems which do not require SecD and SecF for activity, affirm the importance of these proteins to the export process, and suggest that SecD and SecF function together to stimulate protein export in a role fundamentally different from other Sec proteins. Our results provide additional support for the notion that an early step in protein export is cold-sensitive.