Hybrid <i>E. coli</i>—Mitochondrial ribonuclease P RNAs are catalytically active
Bibliographic record
Abstract
RNase P is a ribonucleoprotein that cleaves tRNA precursors at their 5'-end. Mitochondrion-encoded RNA subunits of mitochondrial RNase P (mtP-RNA) have been identified in jakobid flagellates such as Reclinomonas americana, in the prasinophyte alga Nephroselmis olivacea, and in several ascomycete and zygomycete fungi. While the structures of ascomycete mtP-RNAs are highly reduced, those of jakobids, prasinophytes, and zygomycetes retain most conserved features of their bacterial counterparts. Therefore, these mtP-RNAs might be active in vitro in the absence of a protein subunit, as are bacterial P-RNAs. Here we present a comparative structural analysis including seven newly characterized jakobid mtP-RNAs. We investigate ribozyme activities of mtP-RNAs and find that even the most bacteria-like molecules of jakobids are inactive in vitro. However, when certain domains of jakobid and N. olivacea mtP-RNAs are replaced with those from Escherichia coli, these hybrid RNAs show catalytic activity. In vitro mutagenesis of these hybrid mtP-RNAs shows that various structural elements play a critical role in ribozyme catalysis and provide further support for the presence of these elements in mtP-RNAs. These include GNRA tetraloops in helix P14 and P18 of Jakoba libera, and a remnant P3 pairing in Seculamonas ecuadoriensis. Finally, we will discuss reasons for the failure of mtP-RNAs to show catalytic activity in the absence of P-proteins based on our mutagenesis analysis.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".