Palomares-Jerez M Francisca, Nemesio Henrique, Franquelim Henri G, Castanho Miguel A R B, Villalaín José
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, Alicante, Spain.
Biochim Biophys Acta. 2013 Aug;1828(8):1938-52. doi: 10.1016/j.bbamem.2013.04.020. Epub 2013 Apr 29.
HCV NS4B, a highly hydrophobic protein involved in the alteration of the intracellular host membranes forming the replication complex, plays a critical role in the HCV life cycle. NS4B is a multifunctional membrane protein that possesses different regions where diverse and significant functions are located. One of these important regions is the AH2 segment, which besides being highly conserved has been shown to play a significant role in NS4B functioning. We have carried out an in-depth biophysical study aimed at the elucidation of the capacity of this region to interact, modulate and disrupt membranes, as well as to study the structural and dynamic features relevant for that disruption. We show that a peptide derived from this region, NS4BAH2, is capable of specifically binding phosphatidyl inositol phosphates with high affinity, and its interfacial properties suggest that this segment could behave similarly to a pre-transmembrane domain partitioning into and interacting with the membrane depending on the membrane composition and/or other proteins. Moreover, NS4BAH2 is capable of rupturing membranes even at very low peptide-to-lipid ratios and its membrane-activity is modulated by lipid composition. NS4BAH2 is located in a shallow position in the membrane but it is able to affect the lipid environment from the membrane surface down to the hydrophobic core. The NS4B region where peptide NS4BAH2 resides might have an essential role in the membrane replication and/or assembly of the viral particle through the modulation of the membrane structure and hence the replication complex.
丙型肝炎病毒（HCV）非结构蛋白4B（NS4B）是一种高度疏水的蛋白质，参与形成复制复合物的细胞内宿主膜的改变，在HCV生命周期中起关键作用。NS4B是一种多功能膜蛋白，具有不同的区域，这些区域具有多种重要功能。其中一个重要区域是AH2片段，它除了高度保守外，还在NS4B功能中发挥重要作用。我们进行了深入的生物物理研究，旨在阐明该区域与膜相互作用、调节和破坏膜的能力，以及研究与这种破坏相关的结构和动力学特征。我们发现，源自该区域的一种肽NS4BAH2能够以高亲和力特异性结合磷脂酰肌醇磷酸，其界面特性表明，根据膜组成和/或其他蛋白质的不同，该片段的行为可能类似于一个前跨膜结构域，能够插入膜并与膜相互作用。此外，即使在非常低的肽与脂质比例下，NS4BAH2也能够破坏膜，并且其膜活性受脂质组成的调节。NS4BAH2位于膜的浅表层，但它能够从膜表面一直影响到疏水核心的脂质环境。肽NS4BAH2所在的NS4B区域可能通过调节膜结构进而调节复制复合物，在病毒颗粒的膜复制和/或组装过程中发挥重要作用。
