Klug G, Jäger A, Heck C, Rauhut R
Institut für Mikrobiologie und Molekularbiologie der Justus Liebig Universität, Giessen, Germany.
Mol Gen Genet. 1997 Feb 27;253(6):666-73. doi: 10.1007/s004380050370.
The leader peptidase (signal peptidase I) gene, lepB, of Rhodobacter capsulatus has been cloned and sequenced. The amino acid sequence of the predicted protein exhibits similarity to other known bacterial leader peptidases. R. capsulatus belongs to the alpha-subdivision of purple bacteria and thus is a relative of mitochondria in eukaryotes. Like the yeast mitochondrial inner membrane proteases IMP1 and IMP2, the leader peptidase from Rhodobacter has only one membrane-spanning segment. Sequence comparison of the Rhodobacter Lep protein with IMP1 and IMP2 did not reveal a higher overall similarity than between other prokaryotic signal peptidases and the mitochondrial enzymes. Expression studies using lacZ fusions in combination with primer extension analysis provide evidence for a weak promoter located a short distance from the transcription start of the lepB gene. Failure to establish a Rhodobacter strain with a disrupted lepB gene indicates that this gene is essential.
已经克隆并测序了荚膜红细菌的前导肽酶（信号肽酶I）基因lepB。预测蛋白质的氨基酸序列与其他已知细菌前导肽酶具有相似性。荚膜红细菌属于紫色细菌的α-亚类，因此是真核生物中线粒体的亲属。与酵母线粒体内膜蛋白酶IMP1和IMP2一样，来自红细菌的前导肽酶只有一个跨膜区段。红细菌Lep蛋白与IMP1和IMP2的序列比较没有显示出比其他原核信号肽酶与线粒体酶之间更高的总体相似性。使用lacZ融合结合引物延伸分析的表达研究提供了证据，表明在距lepB基因转录起始点短距离处存在一个弱启动子。未能建立具有破坏的lepB基因的红细菌菌株表明该基因是必需的。
