The E3 ligase TRIM56 is a host restriction factor of Zika virus and depends on its RNA-binding activity but not miRNA regulation, for antiviral function

Yang, Darong; Li, Nan L.; Wei, Dahai; Liu, Baoming; Guo, Fang; Elbahesh, Husni; Zhang, Yunzhi; Zhou, Zhi; Chen, Guo-Yun; Li, Kui

To understand how TRIM56 exerts its antiviral action, we determined the domains or activities that are critical for TRIM56 to restrict ZIKV infection. The main functional domains of TRIM56 and its various mutants are illustrated in Fig 4A. We first utilized three cell lines derived from HeLa-FitA2 that stably express, in a Dox-inducible fashion, HA-tagged wildtype TRIM56 (WT), the E3 Ub ligase-deficient CC21/24AA mutant (AA), and the C-terminal aa 693-750 deletion mutant (Mut N), respectively [34] . As shown in Fig 4B, comparable expression of WT TRIM56 and mutant proteins was achieved following Dox treatment. When challenged with ZIKV (MOI = 0.5), cells in which WT TRIM56 was induced harbored substantially lower level of ZIKV E protein than cells without Dox induction (Fig 4B, upper panels, compare lanes 4 vs 3) . In contrast, intracellular ZIKV E protein abundance was unaffected following Dox induction of either the E3 Ub ligase-dead AA mutant or the C-terminal deletion mutant (Mut N) (Fig 4B, middle and lower panels) .