A new preprint on Biorxiv looking at the nuclear translocation of S protein and mRNA in infected cells is attracting a lot of attention online today.
Some of the key points from the preprint:
Here, we first report the nuclear translocation of S protein and mRNA in SARS-CoV-2-infected cells. The translocation of the SARS-CoV-2 S mRNA appeared to be assisted by the S protein, which contains an NLS motif that is unique among human pathogenic beta-coronaviruses.
We investigated whether the S protein translocated into the nucleus in the SARS-CoV-2-infected airway epithelium. Consistent with the S mRNA data, we found that the S protein translocated into the nucleus and was abundant on the cellular surface through the cytoplasmic ER-Golgi pathway.
One of the most important findings in our study was the simultaneous detection of the different spatial distributions of S protein and S mRNA at the single-molecule level in a single infected cell. We confirmed that S mRNA translocated into the nucleus by image analysis of the colocalization of S mRNA with nuclear staining.
In conclusion, the SARS-CoV-2 S protein has a functional pat7 NLS “PRRARSV”, that results in one out of four S proteins translocating into the nucleus in infected cells. S Protein appears to shuttle S mRNA (possibly the genome) into the nucleus as well. Thus, the NLS of the S protein may contribute to the evasion of the host immune response and is a novel pathogenic feature of SARS-CoV-2.