Finding. The helicase that walks trypanosome mitochondrial RNAs through their guide-RNA ladder has a handhold on the proteins at the guide's 5-prime end. Yelmar, Cruz-Reyes, McDermott, Kowalinski and colleagues use proximity labeling and co-immunoprecipitation mass spectrometry to put KREH2 on RESC1-RESC2 in cells. They rebuild a minimal trimer from a KREH2 peptide plus the heterodimer. Cryo-electron microscopy sees the peptide on RESC1. That is a direct bind, not a co-elution rumor, and it sits at the 5-prime end of the guide RNA where the next remodeling step has to start.
Why this paper matters
Uridine insertion/deletion editing is essential in these parasites and absent in people, which is why every new subunit contact is a possible selective surface. Mechanistically it answers a simple missing link: how the DEAH helicase talks to the RESC module. If you already follow editosome papers, this is the KREH2-RESC1 handshake.
What they actually measured
In vivo association, reconstitution, a peptide-resolution cryo-EM. Not a full helicase structure on RNA.
How to read the score
High 70s. Real mitochondrial RNA machine, parasite-specific. Confidence is high for the contact.
Caveats
Peptide, not full-length KREH2 on a guide. No mutant-editing assay in the abstract.
What to do with it
If you purify editosomes, blot KREH2 against RESC1 after a peptide-interface mutation. If you do not work on kinetoplast RNA, skip it.