Prolipoprotein modification and processing in Escherichia coli. A unique secondary structure in prolipoprotein signal sequence for the recognition by glyceryl transferase.
Prolipoprotein modification and processing in Escherichia coli. A unique secondary structure in prolipoprotein signal sequence for the recognition by glyceryl transferase.
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DOI：
10.1111/j.1432-1033.1984.tb08196.x
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发表时间：
1984-06
期刊：
影响因子：
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通讯作者：
C. Giam;Toby Chai;Shigeru Hayashi;Henry C. Wu
中科院分区：
文献类型：
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作者：
C. Giam;Toby Chai;Shigeru Hayashi;Henry C. Wu
大肠杆菌突变体(LPP-14-1)在前脂蛋白信号序列的第14个氨基酸残基上将甘氨酸转变为天冬氨酸，先前已被证明在其细胞膜中含有未经修饰和未加工的前脂蛋白。LPP基因的野生型和LPP-14-1等位基因均已克隆到噬菌体Lambda载体上。LPP-14-1的两个假回复等位基因(14R21和6a)已被分离、克隆和测序。从两个逆转的脂蛋白等位基因的DNA序列推导出的氨基酸序列和逆转的脂蛋白的生化特征表明，天冬氨酸(残基14)转化为天冬酰胺完全恢复了14R21突变的前脂蛋白的修饰和加工，而苏氨酸-16改变为异亮氨酸-16部分增强了6a前脂蛋白的修饰和加工，保留了天冬氨酸-14的取代。根据Chou和Fasman规则对突变的前脂蛋白信号序列的二级结构分析表明，信号序列中14和15残基的特异性卷曲区以及16-18残基的β-折叠结构可能对前脂蛋白的修饰起重要作用。这些结果表明，前脂蛋白信号序列14-18残基的独特二级结构和疏水性对于甘油转移酶的正确识别具有重要作用。
An Escherichia coli mutant (lpp-14-1), with an alteration of glycine to aspartic acid at the 14th amino acid residue of the prolipoprotein signal sequence, has previously been shown to contain unmodified and unprocessed prolipoprotein in its cell envelope. Both the wild-type and the lpp-14-1 alleles of the lpp gene have been cloned onto a phage lambda vector. Two pseudorevertant alleles of lpp-14-1 (14R21 and 6a) have been isolated, cloned and sequenced. Amino acid sequences, deduced from the DNA sequences of the two revertant lipoprotein alleles, and biochemical characterization of the revertant lipoproteins, show that a conversion of the aspartic acid (residue 14) to asparagine completely restores the modification and processing of the 14R21 revertant prolipoprotein, while a change of the threonine-16 to isoleucine-16 partially enhances the modification and processing of the 6a prolipoprotein, which retains the aspartate-14 substitution. Secondary structure analysis of the revertant prolipoprotein signal sequences according to the Chou and Fasman rules revealed that the specific coil region in residues 14 and 15, and the beta-sheet structure in residues 16-18 of signal sequence may be important for prolipoprotein modification. These results suggest essential roles of both a unique secondary structure and hydrophobicity in residues 14-18 of prolipoprotein signal sequence for the proper recognition by the glyceryl transferase.