Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) have emerged as important innate immune effectors that prevent diverse virus infections in vertebrates. However, the cellular mechanisms and live-cell imaging of these small membrane proteins have been challenging to evaluate during viral entry of mammalian cells. Using CRISPR–Cas9-mediated IFITM-mutant cell lines, we demonstrate that human IFITM1, IFITM2 and IFITM3 act cooperatively and function in a dose-dependent fashion in interferon-stimulated cells. Through site-specific fluorophore tagging and live-cell imaging studies, we show that IFITM3 is on endocytic vesicles that fuse with incoming virus particles and enhances the trafficking of this pathogenic cargo to lysosomes. IFITM3 trafficking is specific to restricted viruses, requires S-palmitoylation and is abrogated with loss-of-function mutants. The site-specific protein labeling and live-cell imaging approaches described here should facilitate the functional analysis of host factors involved in pathogen restriction as well as their mechanisms of regulation.

Organophosphorus-based nerve agents, such as paraoxon, parathion, and malathion, inhibit acetylcholinesterase, which results in paralysis, respiratory failure, and death. Bacteria are known to use the enzyme phosphotriesterase (PTE) to break down these compounds. In this work, we designed vacancy-engineered nanoceria (VE CeO2 NPs) as PTE mimetic hotspots for the rapid degradation of nerve agents. We observed that the hydrolytic effect of the nanomaterial is due to the synergistic activity between both Ce(3+) and Ce(4+) ions located in the active site-like hotspots. Furthermore, the catalysis by nanoceria overcomes the product inhibition generally observed for PTE and small molecule-based PTE mimetics.

Nanomaterials-based enzyme mimetics (nanozymes) have attracted considerable interest due to their applications in imaging, diagnostics, and therapeutic treatments. Particularly, metal-oxide nanozymes have been shown to mimic the interesting redox properties and biological activities of metalloenzymes. Here we describe an efficient synthesis of MnFe2 O4 nanomaterials and show how the morphology can be controlled by using a simple co-precipitation method. The nanomaterials prepared by this method exhibit a remarkable oxidase-like activity. Interestingly, the activity is morphology-dependent, with nanooctahedra (NOh) exhibiting a catalytic efficiency of 2.21×10(9)  m(-1)  s(-1) , the highest activity ever reported for a nanozyme.

Organophosphorus-based nerve agents,s uch as paraoxon, parathion, and malathion, inhibit acetylcholinesterase,w hich results in paralysis,r espiratory failure,a nd death. Bacteria are knownt ou se the enzyme phosphotriesterase (PTE) to break down these compounds.I nt his work, we designed vacancy-engineered nanoceria (VE CeO 2 NPs) as PTE mimetic hotspots for the rapid degradation of nerve agents.W eo bserved that the hydrolytic effect of the nanomaterial is due to the synergistic activity between both Ce 3+ and Ce 4+ ions located in the active site-like hotspots.F urthermore, the catalysis by nanoceria overcomes the product inhibition generally observed for PTE and small molecule-based PTE mimetics.

Highlights d Photo-crosslinking proteomics identify VCP/p97 as an IFITM3-interacting protein d Ubiquitination of IFITM3 is crucial for interaction with VCP d Lysine 24 ubiquitination regulates IFITM3 trafficking and turnover d Depletion or inhibition of VCP leads to delayed turnover and accumulation of IFITM3