Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308 Gdańsk, Poland.
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland.
Biochim Biophys Acta Biomembr. 2023 Dec;1865(8):184200. doi: 10.1016/j.bbamem.2023.184200. Epub 2023 Jul 29.
Herpes simplex virus 1 (HSV-1) is a well-studied herpesvirus that causes various human diseases. Like other herpesviruses, HSV-1 produces the transmembrane glycoprotein N (gN/UL49.5 protein), which has been extensively studied, but its function in HSV-1 remains largely unknown. The amino-acid sequences and lengths of UL49.5 proteins differ between herpesvirus species. It is, therefore, crucial to determine whether and to what extent the spatial structure of UL49.5 orthologs that are transporter associated with antigen processing (TAP) inhibitors (i.e., of bovine herpesvirus 1; BoHV-1) differ from that of non-TAP inhibitors (i.e., of HSV-1). Our study aimed to examine the 3D structure of the HSV-1-encoded UL49.5 protein in an advanced model of the endoplasmic reticulum (ER) membrane using circular dichroism, 2D nuclear magnetic resonance, and multiple-microsecond all-atom molecular dynamics simulations in an ER membrane mimetic environment. According to our findings, the N-terminus of the HSV-1-encoded UL49.5 adopts a highly flexible, unordered structure in the extracellular part due to the presence of a large number of proline and glycine residues. In contrast to the BoHV-1-encoded homolog, the transmembrane region of the HSV-1-encoded UL49.5 is formed by a single long transmembrane α-helix, rather than two helices oriented perpendicularly, while the cytoplasmic part of the protein (C-terminus) has a short unordered structure. Our findings provide valuable experimental structural information on the HSV-1-encoded UL49.5 protein and offer, based on the obtained structure, insight into its lack of biological activity in inhibiting the TAP-dependent antigen presentation pathway.
单纯疱疹病毒 1（HSV-1）是一种研究充分的疱疹病毒，可引起多种人类疾病。与其他疱疹病毒一样，HSV-1 产生跨膜糖蛋白 N（gN/UL49.5 蛋白），该蛋白已被广泛研究，但它在 HSV-1 中的功能仍知之甚少。UL49.5 蛋白的氨基酸序列和长度在疱疹病毒种间存在差异。因此，确定牛疱疹病毒 1（BoHV-1）等转运蛋白相关抗原加工（TAP）抑制剂的 UL49.5 同源物的空间结构是否以及在何种程度上与非 TAP 抑制剂（如 HSV-1）的结构不同，这一点至关重要。我们的研究旨在使用圆二色性、二维核磁共振和 ER 膜模拟环境中的多微秒全原子分子动力学模拟，在 ER 膜的先进模型中研究 HSV-1 编码的 UL49.5 蛋白的 3D 结构。根据我们的发现，由于存在大量脯氨酸和甘氨酸残基，HSV-1 编码的 UL49.5 的 N 端在细胞外部分呈现高度灵活、无序的结构。与 BoHV-1 编码的同源物不同，HSV-1 编码的 UL49.5 的跨膜区由单个长跨膜α螺旋组成，而不是垂直取向的两个螺旋，而该蛋白的细胞质部分（C 端）具有短的无序结构。我们的发现为 HSV-1 编码的 UL49.5 蛋白提供了有价值的实验结构信息，并根据获得的结构，深入了解其缺乏抑制 TAP 依赖性抗原呈递途径的生物活性。
