Mitchell C, Oliver D
Department of Microbiology, State University of New York at Stony Brook 11794.
Mol Microbiol. 1993 Nov;10(3):483-97. doi: 10.1111/j.1365-2958.1993.tb00921.x.
Six putative ATP-binding motifs of SecA protein were altered by oligonucleotide-directed mutagenesis to try to define the ATP-binding regions of this multifunctional protein. The effects of the mutations were analysed by genetic and biochemical assays. The results show that SecA contains two essential ATP-binding domains. One domain is responsible for high-affinity ATP binding and contains motifs A0 and B0, located at amino acid residues 102-109 and 198-210, respectively. A second domain is responsible for low-affinity ATP binding and contains motifs A3 and a predicted B motif located at amino acid residues 503-511 and 631-653, respectively. The ATP-binding properties of both domains were essential for SecA-dependent translocation ATPase and in vitro protein translocation activities. The significance of these findings for the mechanism of SecA-dependent protein translocation is discussed.
通过寡核苷酸定向诱变改变了SecA蛋白的六个假定的ATP结合基序，以试图确定这种多功能蛋白的ATP结合区域。通过遗传和生化分析来分析这些突变的影响。结果表明，SecA含有两个必需的ATP结合结构域。一个结构域负责高亲和力ATP结合，包含分别位于氨基酸残基102 - 109和198 - 210处的基序A0和B0。第二个结构域负责低亲和力ATP结合，包含分别位于氨基酸残基503 - 511和631 - 653处的基序A3和一个预测的B基序。两个结构域的ATP结合特性对于依赖SecA的转运ATP酶和体外蛋白质转运活性都是必不可少的。讨论了这些发现对于SecA依赖的蛋白质转运机制的意义。
