Yan Li, Young Mee Kim, Jing Zou, Qing-Yin Wang, Shovanlal Gayen, Ying Lei Wong, Le Tian Lee, Xuping Xie, Qiwei Huang, Julien Lescar, Pei-Yong Shi, CongBao Kang, Secondary structure and membrane topology of dengue virus NS4B N-terminal 125 amino acids, Biochimica et Biophysica Acta (BBA) - Biomembranes, Available online 25 September 2015, ISSN 0005-2736, http://dx.doi.org/10.1016/j.bbamem.2015.09.016. (http://www.sciencedirect.com/science/article/pii/S0005273615003016)
The transmembrane NS4B protein of dengue virus (DENV) is a validated antiviral target that plays important roles in viral replication and invasion of innate immune response. The first 125 amino acids of DENV NS4B are sufficient for inhibition of alpha/beta interferon signaling. Resistance mutations to NS4B inhibitors are all mapped to the first 125 amino acids. In this study, we expressed and purified a protein representing the first 125 amino acids of NS4B (NS4B1-125). This recombinant NS4B1-125 protein was reconstituted into detergent micelles. Solution NMR spectroscopy demonstrated that there are five helices (α1 to α5) present in NS4B1-125. Dynamic studies, together with a paramagnetic relaxation enhancement experiment demonstrated that four helices, α2, α3, α4, and α5 are embedded in the detergent micelles. Comparison of wild type and V63I mutant (a mutation that confers resistance to NS4B inhibitor) NS4B1-125 proteins demonstrated that V63I mutation did not cause significant conformational changes, however, V63 may have a molecular interaction with residues in the α5 transmembrane domain under certain conditions. The structural and dynamic information obtained in study is helpful to understand the structure and function of NS4B.
A*STAR BMRC IAF grant (111105), JCO grants (1331A028, 1231B015), National Research Foundation (CRP2008), National Medical Research Council Translational Clinical Research STOP dengue grant (NMRC/TCR/005/2008).