Nah, probably the end of the road for us with this particular project (blame UKRI)

They even made an interactive evidence map:
research.ukhsa.gov.uk/evidence-gap...

Particularly relevant on a day when the first reports have emerged of imported Oropouche cases in the UK:
www.gov.uk/government/n...

It's a lie....🤫

Want to know more? Come to the talk by @danielacl.bsky.social today at #IHW2025 (room 2 at 11:39) or come to her poster tonight (number 3.14).

Congratulations to primary authors Holly and @danielacl.bsky.social on their first first-author research papers. This work was a fun collaboration with @deanelab.bsky.social, and many thanks to @bsfcharity.bsky.social for funding.

While pUL21 doesn’t bind a new surface on PP1, so no new antiviral drugs 😢, we have identified a new mode of PP1 binding via an extended beta sheet…this binding of a protein with no canonical SLiMs to PP1 suggests there might be many more PP1 adaptors in the cell than previously suggested.

Why would a virus keep a suboptimal RVxF motif rather than evolve higher affinity? We hypothesise that it is an additional layer of regulation, make sure that PP1 recruitment only happens in the right place, and at the right time post-infection, when local concentrations of pUL21/pORF38 are high.

However, the affinity of pORF38 for PP1 is ~10-fold lower than for some cellular PP1 binders. This is because these pUL21 and pORF38 residues structurally corresponding to the RVxF motif have non-optimal sequences. Mutating these residues to make a canonical RVxF motif enhances PP1 binding.

Using fluorescence polarization, we showed the TROPPO peptide alone is not enough to bind PP1, you need the whole protein. Also, we show that VZV pORF38 directly competes with cellular RVxF+ϕϕ[xF] motif containing peptides for binding the RVxF motif.

This explains why deleting a chunk of the linker between the pUL21 N-terminal domain (NTD) and the TROPPO motifs abolishes PP1 binding, why our previous TROPPO mutations prevent binding (they would block packing of the TROPPO and the pUL21 NTD), and new mutations further supported the #AF3 models.

Using #AlphaFold3, we predicted the structure of HSV-1 pUL21 and VZV pORF38 in complex with PP1. Surprisingly, the TROPPO motif binds the same hydrophobic groove as cellular RVxF and ϕϕ[xF] motifs. Strikingly, a disordered linker region of pUL21 is predicted to become ordered upon PP1 binding.

This TROPPO motif is conserved across the alphaherpesviruses, but it doesn’t resemble any of the known PP1 binding motifs (RVxF, SILK, ϕϕ[xF], etc.). Does that mean pUL21 and homologues bind PP1 via a novel surface, that could be targeted with antiviral drugs?

We showed a few years ago that HSV pUL21 is a PP1 adaptor protein, directing dephosphorylation of cellular and viral proteins, and that PP1 recruitment requires a novel motif: TROPPO (a tenuous bacronym 😉)