Palomares-Jerez F, Nemesio Henrique, Villalaín José
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, E-03202 Elche-Alicante, Spain.
Biochim Biophys Acta. 2012 Dec;1818(12):2958-66. doi: 10.1016/j.bbamem.2012.07.022. Epub 2012 Aug 1.
Determination of the membrane spanning domains of highly hydrophobic proteins from its primary structure, i.e., sequence, is cumbersome. However, transmembrane topology is better correlated with protein secondary structure than with the primary one. In this work we have determined the number and location of the transmembrane domains of the highly hydrophobic hepatitis C virus NS4B protein by studying the water-to-bilayer and water-to-interface transfer free energies of thirty-one different hepatitis C virus strains assuming that NS4B forms an α-helical wheel. Additionally, we have studied the effect of a peptide library encompassing the full length of the NS4B protein hepatitis C virus strain 1a_H77 on the phase transitions of DEPE through the use of differential scanning calorimetry. Our findings show that NS4B protein has five transmembrane domains and, as previously suggested, three interfacial segments. One of these segments, segment AH2, could behave similarly to viral pre-transmembrane segments, which would partition into and interact with the membrane and be responsible for the fluctuation of the protein between different topologies and therefore possible locations.
从高度疏水蛋白质的一级结构（即序列）确定其跨膜结构域很麻烦。然而，跨膜拓扑结构与蛋白质二级结构的相关性比与一级结构的相关性更好。在这项工作中，我们通过研究31种不同丙型肝炎病毒株的从水到双层膜以及从水到界面的转移自由能，确定了高度疏水的丙型肝炎病毒NS4B蛋白跨膜结构域的数量和位置，假设NS4B形成一个α-螺旋轮。此外，我们通过差示扫描量热法研究了包含丙型肝炎病毒1a_H77株NS4B蛋白全长的肽库对二油酰磷脂酰乙醇胺（DEPE）相变的影响。我们的研究结果表明，NS4B蛋白有五个跨膜结构域，并且如先前所暗示的，有三个界面区段。其中一个区段，即AH2区段，其行为可能类似于病毒跨膜前区段，该区段会分配到膜中并与膜相互作用，负责蛋白质在不同拓扑结构之间的波动，从而可能导致不同的定位。
