# Resurrecting the Activity of the RNA Subunit of Human RNase P

## TL;DR

Researchers improved the activity of a human RNA enzyme by introducing structural changes inspired by bacterial RNA, showing that specific RNA elements can enhance its function.

## Contribution

The study demonstrates that introducing bacterial-like RNA elements can significantly enhance the catalytic activity of human H1 RNA.

## Key findings

- Modifying the P4-J19/4 region increased H1 RNA activity by two-fold.
- Combining P4-J19/4 with P2-P3-J3/4 and P5-P15 elements increased activity by five-fold.
- Bacterial RnpA protein can activate human H1 RNA variants at low Mg2+ concentrations.

## Abstract

The RNA subunit of human nuclear RNase P, H1 RNA, has low catalytic activity in the absence of its protein cofactors. To improve H1 RNA activity, we introduced minor structural changes toward the bacterial consensus into its catalytic (C) domain. Incorporating a bacterial‐like P4‐J19/4 element increased its ribozyme activity ∼two fold. Changes toward bacterial‐like P2‐P3‐J3/4 or P5‐P15 elements individually impaired its activity, but increased activity ∼five fold when combined with a bacterial P4‐J19/4 element, suggesting that several core elements act cooperatively to enhance the catalytic performance of H1 RNA. Neither fusion of the H1 RNA C‐domain to the bacterial S‐domain nor substrate tethering to H1 RNA resulted in detectable cleavage activity, indicating that low H1 RNA activity is not merely a consequence of defective S‐domain function. Pb2+‐probing and UV melting profiles indicate an inherently unstable global structure of H1 RNA that is sensitive to structural alterations. The parental H1 RNA and its two to five fold more active variants could be activated by the Escherichia coli RNase P (RnpA) protein at low (10 mM) Mg2+ concentration, indicating that bacterial RnpA and eukaryotic Pop5 protein subunits recognize C‐domain core elements common to all RNase P RNAs.

The catalytic RNA (H1 RNA) of the human nuclear tRNA processing enzyme RNase P has >105‐fold lower activity in the absence of its 11 protein cofactors than bacterial RNase P RNAs. By introducing mutations toward the bacterial consensus into its catalytic domain, a two and fivefold activity enhancement could be achieved by changes in the P4‐19/4 region alone and combined with changes in the P2‐3_J3/4 and J4/7_J7/2 regions, respectively.© 2026 WILEY‐VCH GmbH