Abstract
The Escherichia coli ribonuclease P (RNase P) has a protein component, termed C5, which acts as a cofactor for the catalytic M1 RNA subunit that processes the 5′ leader sequence of precursor tRNA. Rpp29, a conserved protein subunit of human RNase P, can substitute for C5 protein in reconstitution assays of M1 RNA activity. To better understand the role of the former protein, we compare the mode of action of Rpp29 to that of the C5 protein in activation of M1 RNA. Enzyme kinetic analyses reveal that complexes of M1 RNA-Rpp29 and M1 RNA-C5 exhibit comparable binding affinities to precursor tRNA but different catalytic efficiencies. High concentrations of substrate impede the activity of the former complex. Rpp29 itself exhibits high affinity in substrate binding, which seems to reduce the catalytic efficiency of the reconstituted ribonucleoprotein. Rpp29 has a conserved C-terminal domain with an Sm-like fold that mediates interaction with M1 RNA and precursor tRNA and can activate M1 RNA. The results suggest that distinct protein folds in two unrelated protein cofactors can facilitate transition from RNA- to ribonucleoprotein-based catalysis by RNase P.
| Original language | English |
|---|---|
| Pages (from-to) | 5120-5132 |
| Number of pages | 13 |
| Journal | Nucleic Acids Research |
| Volume | 33 |
| Issue number | 16 |
| DOIs | |
| State | Published - 2005 |
Bibliographical note
Funding Information:We thank Sidney Altman (Yale University) for providing us with recombinant C5 protein and anti-C5 protein antibodies. Y.B.A., a postdoctoral fellow, is supported in part by the anonymous fund with Dr Nemeth, Friends of the Hebrew University, UK. This research is supported by the United States-Israel Binational Science Foundation (grant no. 2001-017), the Israel Science Foundation (grant no. 549/01) and the Abisch-Frenkel Foundation (Switzerland) to N.J. Funding to pay the Open Access publication charges for this article was provided by United States-Israel Binational Science Foundation.