Signal Sequences: Roles and Interactions by Biophysical Methods
Signal Sequences: Roles and Interactions by Biophysical Methods
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信号序列：生物物理方法的作用和相互作用
DOI：
10.1007/978-3-642-78846-8_18
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
L. Gierasch
中科院分区：
文献类型：
--
作者：
L. Gierasch
信号序列对于有效和选择性地将新生蛋白质链靶向内质网、真核生物或原核生物的细胞膜是必不可少的(有关综述，请参阅Gierasch，1989)。此外，信号序列在多肽链跨膜转移中发挥着中心作用，尽管人们对此知之甚少。尽管信号序列具有执行多种常见功能的能力，但它们缺乏初级结构同源性。相反，它们有几个共同的一般性质(von Heijne，1985)：(1)一个带净正电荷的氨基末端区域；(2)一个约10个残基的疏水核心；(3)在切割位点之前的6-8个残基的位置，它通常包含一个Pro或甘氨酰残基，并具有相对较高的预测转向倾向；(4)在切割位置有一个基序--原核生物或小型真核生物中的AXA。这些共同的特征以及信号序列通常可以在保留功能的情况下从一个分泌蛋白转移到另一个分泌蛋白的发现，促使人们使用物理方法对分离的信号肽进行研究，这可能揭示这些有趣序列的构象和相互作用倾向。这些信息可以帮助阐明信号序列在输出途径中的可能作用。此外，分离的信号肽可以作为信号序列与输出途径的蛋白质相互作用的探针。通过比较出口活性信号肽和出口缺陷突变体对应的多肽的性质，我们发现所有的功能信号肽都具有在膜环境中形成α螺旋的能力和自发插入膜的酰基链区域的能力(Briggs&Gierasch，1984；Briggs等，1985；McKnight等，1989；Hoyt&Gierasch，1991a，1991b)。以圆二色谱(CD)和核磁共振(NMR)为主要手段，测定了其构象行为，并用荧光光谱分析了膜的插入情况。最近，我们开发了一种水溶性增强的信号肽，以便应用转移核Overhauser增强(TrNOEs)的方法来直接确定脂双层中信号肽的构象。我们从这些研究和我们的荧光工作中发现，信号肽的疏水核心很好地嵌入在双层的酰基链区中，形成稳定的α螺旋，而N-末端区域与表面结合。C-末端片段采用了不太稳定的α螺旋，并似乎在界面上停留了一段时间。羊信号肽的荧光猝灭结果不支持稳定的跨膜排列；这项工作正在进行中，以确定这种行为是否普遍，以及超过切割位点的额外残基会产生什么影响。
Signal sequences are essential for the efficient and selective targeting of nascent protein chains either to the endoplasmic reticulum, in eukaryotes, or to the cytoplasmic membrane, in prokaryotes (for a review, see Gierasch, 1989). Furthermore, signal sequences play a central, although poorly understood, role in the translocation of polypeptide chains across membranes. Despite their ability to perform multiple, common functions, signal sequences lack primary structural homology. Instead, they share several general properties (von Heijne, 1985): (1) an amino-terminal region with a net positive charge; (2) a hydrophobic core of about ten residues; (3) a locus six to eight residues preceding the cleavage site that often contains a prolyl or glycyl residue and has a relatively high predicted turn tendency; and (4) a motif at the cleavage site--AXA in prokaryotes or small-largesmall in eukaryotes. These shared features and the finding that signal sequences are often transportable from one secreted protein to another with retention of function invite the study of isolated signal peptides using physical methods that may reveal the conformational and interactive propensities of these intriguing sequences. This information then can help to elucidate the likely roles of signal sequences in the export pathway. Also, the isolated signal peptides can serve as probes for the interactions of the signal sequence with proteins of the export pathway. By comparing properties of export-competent signal peptides with those of peptides corresponding to export-defective mutants, we have found that all functional signal peptides have both a capacity to form an α helix in membrane environments and an ability to spontaneously insert into the acyl chain region of a membrane (Briggs & Gierasch, 1984; Briggs et al., 1985; McKnight et al.,1989; Hoyt & Gierasch, 1991a, 1991b). As principal methods, we have used circular dichroism (CD) and nuclear magnetic resonance (NMR) to determine the conformational behavior and fluorescence spectroscopy to analyze membrane insertion. Recently, we have developed a signal peptide of enhanced water solubility in order to apply the method of transferred nuclear Overhauser enhancements (trNOEs) to determine directly the conformation of a signal peptide in a lipid bilayer. We find from these studies and our fluorescence work that the hydrophobic core of the signal peptide resides well-embedded in the acyl chain region of the bilayer in a stable α helix, while the N-terminal region associates with the surface. The C-terminal segment adopts a less stable α helix and appears to spend some time at the interface. Fluorescence quenching results on the LamB signal peptide do not support a stable transmembrane arrangement;. work is in progress to establish whether this behavior is general and what the influence is of additional residues past the cleavage site.
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影响因子：
2.9
作者：
CHATTOPADHYAY, A;LONDON, E
通讯作者：
LONDON, E
探索信号序列的构象作用：λ受体蛋白野生型和突变信号肽的合成和构象分析。
影响因子：
2.9
作者：
Briggs,MS;Gierasch,LM
通讯作者：
Gierasch,LM
与疏水核心中带有天冬酰胺的输出缺陷突变体 OmpA 信号序列相对应的肽无法插入模型膜中。
DOI：
--
发表时间：
1991
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Hoyt,DW;Gierasch,LM
通讯作者：
Gierasch,LM
野生型和突变型 OmpA 信号肽的疏水含量和脂质相互作用与其体内功能相关。
影响因子：
2.9
作者：
Hoyt,DW;Gierasch,LM
通讯作者：
Gierasch,LM
大肠杆菌 OmpA 信号肽疏水区内缺失突变对两种杂合蛋白的不同影响。
DOI：
--
发表时间：
1987
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Lehnhardt,S;Pollitt,S;Inouye,M
通讯作者：
Inouye,M