Summary
A bioRxiv preprint reports that the host protein HNRNPM binds stem-loop 5 in the SARS-CoV-2 5′-UTR and promotes protein synthesis from the viral RNA. Mutations in the structure’s lower stem reduced both HNRNPM binding and protein synthesis.
A bioRxiv preprint reports that the human host protein HNRNPM interacts with stem-loop 5 (SL5), a structured region in the SARS-CoV-2 RNA, and promotes protein synthesis from the virus’s 5′ untranslated region (5′-UTR). The authors also report that changes to the lower part of SL5 weaken HNRNPM binding and reduce protein synthesis.
How HNRNPM interacts with viral RNA
The 5′-UTR is a non-protein-coding stretch at the beginning of the virus’s RNA genome. It can fold into structures that help regulate how viral proteins are made. The preprint describes five conserved stem-loops in this region; SL5 includes the start codon for non-structural protein 1, or nsp1.
The authors report that HNRNPM moves into the cell’s cytoplasm during SARS-CoV-2 infection and functionally interacts with SL5. When they altered the lower stem of SL5, HNRNPM binding and protein synthesis fell. This links the structure of that RNA region to both protein binding and the production of proteins from the viral 5′-UTR, although the abstract does not give the size of those changes or detail the assays used.
The preprint also reports that the HNRNPM–SL5 interaction is conserved among different alpha- and betacoronaviruses. That points to a potentially shared feature of coronavirus RNA regulation, rather than one confined to SARS-CoV-2.
Why the finding matters
Viruses depend on host-cell machinery to make proteins from their genetic material. Identifying a host protein that interacts with a conserved viral RNA structure adds a possible regulatory step to the picture of how coronavirus translation works. The authors interpret their findings as evidence that HNRNPM can promote SARS-CoV-2 replication by regulating viral protein synthesis.
This is a molecular virology finding reported in a preprint, not a study of patients or a test of a treatment. Its relevance is in clarifying a host–virus interaction that researchers can investigate further.