Andersson H, von Heijne G
Department of Molecular Biology, Karolinska Institute Center for Structural Biochemistry, NOVUM, Huddinge, Sweden.
J Biol Chem. 1993 Oct 5;268(28):21389-93.
Positively charged amino acids are major determinants of the topology of bacterial inner membrane proteins, whereas negatively charged residues by themselves have little or no influence on the transmembrane orientation. Further, positively charged amino acids can very efficiently block the function of signal sequences when placed immediately downstream, while negatively charged residues are much less potent also in this regard. Here, we show that a negatively charged aspartic acid situated close to a positively charged lysine can attenuate both of these effects in a position-specific manner, suggesting that intra- or intermolecular charge pairing can modulate the interactions between positively charged residues in the nascent chain and parts of the secretory machinery or membrane phospholipids. These observations further underscore the importance of charged amino acids during protein translocation and membrane protein assembly.
带正电荷的氨基酸是细菌内膜蛋白拓扑结构的主要决定因素，而带负电荷的残基本身对跨膜方向几乎没有影响。此外，当带正电荷的氨基酸紧邻信号序列下游放置时，能非常有效地阻断信号序列的功能，而在这方面带负电荷的残基效力要低得多。在此，我们表明，靠近带正电荷赖氨酸的带负电荷天冬氨酸可以以位置特异性方式减弱这两种效应，这表明分子内或分子间电荷配对可以调节新生链中带正电荷残基与分泌机制或膜磷脂部分之间的相互作用。这些观察结果进一步强调了带电荷氨基酸在蛋白质转运和膜蛋白组装过程中的重要性。
