Davis N G, Hsu M C
Proc Natl Acad Sci U S A. 1986 Jul;83(14):5091-5. doi: 10.1073/pnas.83.14.5091.
Recent work on a prokaryotic membrane protein, gene III protein (pIII) of coliphage f1, showed that polypeptide segments of sufficient hydrophobicity functioned to stop transfer of the polypeptide across the cell membrane: strings of 16 or more hydrophobic amino acids sufficed. A fusion-related hydrophobic domain (FRHD) of Sendai F protein, a sequence of 26 consecutive uncharged residues, has been implicated in the fusion of the viral membrane envelope and the target-cell membrane through a hydrophobic interaction. As it is located on the exterior of the viral membrane, this sequence must be transferred across the host-cell membrane during synthesis. We have inserted either the FRHD or the F protein membrane anchor (the COOH-terminal region of the F protein) into an internal site of a secreted pIII, which lacks its natural membrane anchor. These two hydrophobic sequences behave in the bacteria just as they do in their natural eukaryotic cell host. The F protein membrane anchor functions to stop transfer, conferring a membrane-spanning topology to the F-pIII hybrid protein; however, the FRHD is moved through the cytoplasmic membrane and derivatives carrying this sequence are secreted to the periplasm. We discuss how the FRHD is compatible with passage through the membrane and yet is still able to mediate membrane fusion through a presumed hydrophobic interaction.
最近对一种原核膜蛋白——大肠杆菌噬菌体f1的基因III蛋白（pIII）的研究表明，具有足够疏水性的多肽片段能够阻止多肽穿过细胞膜：16个或更多疏水氨基酸的序列就足够了。仙台病毒F蛋白的融合相关疏水结构域（FRHD），即一段连续26个不带电荷残基的序列，已被认为通过疏水相互作用参与病毒膜包膜与靶细胞膜的融合。由于它位于病毒膜的外部，该序列在合成过程中必须穿过宿主细胞膜。我们将FRHD或F蛋白膜锚定序列（F蛋白的COOH末端区域）插入到缺乏天然膜锚定序列的分泌型pIII的内部位点。这两个疏水序列在细菌中的行为与在它们天然的真核细胞宿主中的行为相同。F蛋白膜锚定序列起到阻止转移的作用，赋予F-pIII杂合蛋白跨膜拓扑结构；然而，FRHD穿过细胞质膜，携带该序列的衍生物被分泌到周质中。我们讨论了FRHD如何既能与穿过膜兼容，又仍能通过推测的疏水相互作用介导膜融合。
