Figure 4.

SARS-CoV-2 N protein is an interacting partner of TRIM25. The ability of SARS-CoV-2 N protein to interact with TRIM25 and RIG-I was determined by co-immunoprecipitation (Co-IP) on lysates of transfected Lenti-X 293T cells. (A) The formation of a stable immune complex was detected when TRIM25 was transiently over-expressed along with the N protein following Co-IP with anti-HA. (B) The N viral protein presented affinity with the SPRY domain of TRIM25 because the viral protein was detected in the anti-HA Co-IP performed on lysates of Lenti-X 293T cells expressing HA-SPRY, alone or in combination with the N protein. (C) The capability of SARS-CoV-2 N protein to disturb the RIG-I-TRIM25 interaction was then investigated by Co-IP on lysates of Lenti-X 293T cells simultaneously expressing RIG-I, TRIM25 and N. The interaction between RIG-I and TRIM25 was not affected by the presence of the viral protein. Indeed, their interaction was detected as co-immunoprecipitating with anti-HA antibody in the samples in which the N protein was either present or absent. Blots are representative of (n = 3) independent experiments. Fifty micrograms of WCLs were loaded on SDS-PAGE and immunostained as protein expression controls.