Ebola virus VP35 has novel NTPase and helicase-like activities

Shu, Ting; Gan, Tianyu; Bai, Peng; Wang, Xiaotong; Qian, Qi; Zhou, Hui; Cheng, Qi; Qiu, Yang; Yin, Lei; Zhong, Jin; Zhou, Xi

Previous studies have revealed that EBOV VP35 is a multifunctional protein with dsRNA-binding activity that is important for its ability to suppress immune responses (31, 43, 44) . To further characterize EBOV VP35, it was fused with maltose-binding protein at its N-terminal (MBP-VP35) and then purified (Supplementary Figure S1 ). Previous studies have uncovered that EBOV VP35 can be oligomerized (33, 45) . To examine if the purified MBP-VP35 is oligomeric (33,46), MBP-VP35 was purified via MBP column and ion-exchange (Supplementary Figure S2A) , and then subjected to the size-exclusion chromatography analysis using a Superdex 200 column. The purified MBP-VP35 proteins were eluted in the major peak that should correspond to a molecular mass of ∼600 kDa, while monomeric BSA was used as a control that was eluted in its correct size of ∼67 kDa (Supplementary Figure S2B) . Although the effect of shape on elution on size exclusion column makes it hard to calculate the exact molecular mass of the MBP-VP35 complex, these results indicate that the purified recombinant MBP-VP35 should be in an oligomeric form.