ROLE OF POSITIVE CHARGE ON THE AMINO-TERMINAL REGION OF THE SIGNAL PEPTIDE IN PROTEIN SECRETION ACROSS THE MEMBRANE
ROLE OF POSITIVE CHARGE ON THE AMINO-TERMINAL REGION OF THE SIGNAL PEPTIDE IN PROTEIN SECRETION ACROSS THE MEMBRANE
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DOI：
10.1073/pnas.79.11.3438
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发表时间：
1982-01-01
期刊：
影响因子：
--
通讯作者：
INOUYE, M
中科院分区：
文献类型：
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作者：
INOUYE, S;SOBERON, X;INOUYE, M
正电荷的信号肽的氨基末端区域被认为在蛋白质跨膜分泌的初始步骤中具有重要作用（环模型）。为了验证这一假设，通过使用合成的寡核苷酸，通过对携带诱导型脂蛋白基因的质粒DNA进行定向位点特异性诱变，将大肠杆菌外膜的前脂蛋白的信号肽的氨基末端区域上的电荷从+2改变为+1，0和-1。本节的野生型序列。图形 **。因此，将其变更为Met-Lys-Asp-Thr-Lys（I-1; +1）、Met-Ala-Thr-Lys（I-2; +1）、Met-Asp-Thr-Lys（I-3; 0）和Met-Glu-Asp-Thr-Lys（I-4; -1）。诱导脂蛋白产生后，用[35 S]甲硫氨酸脉冲标记细胞10秒。I-1、I-2和I-3的脂蛋白在膜中组装，尽管脂蛋白产生的速率随着信号肽上的电荷变得更负而逐渐降低。在I-4的情况下，只有少量的脂蛋白组装在膜上，而大量的甘油未修饰的前脂蛋白积累在细胞质中。这种可溶性脂蛋白前体是逐渐分泌的，并在膜上进行修饰和组装。信号肽的带正电荷的氨基末端区域显然在跨膜的有效蛋白质分泌中起重要作用。
The positively charged amino-terminal region of the signal peptide is proposed to have an important role at an initial step of protein secretion across the membrane (loop model). To test this hypothesis, the charge on the amino-terminal region of the signal peptide of the prolipoprotein of the Escherichia coli outer membrane was altered by using synthetic oligonucleotides from +2 to +1, 0 and -1 by guided site-specific mutagenesis of a plasmid DNA carrying an inducible lipoprotein gene. The wild-type sequence of this section, .**GRAPHIC**. was thus changed to Met-Lys-Asp-Thr-Lys (I-1; +1), Met-Ala-Thr-Lys (I-2; +1), Met-Asp-Thr-Lys (I-3; 0), and Met-Glu-Asp-Thr-Lys (I-4; -1). After induction of lipoprotein production, cells were pulse labeled with [35S]methionine for 10 s. The lipoprotein of I-1, I-2, and I-3 was assembled in the membrane, although the rates of lipoprotein production progressively decreased as the charge on the signal peptide became more negative. In the case of I-4, only a small amount of lipoprotein assembled in the membrane while a large amount of glycerol-unmodified prolipoprotein accumulated in the cytoplasm. This soluble prolipoprotein was gradually and posttranslationally secreted across the membrane to be modified and assembled in the membrane. The positively charged amino-terminal region of the signal peptide apparently plays an important role in efficient protein secretion across the membrane.