Four Inteins and Three Group II Introns Encoded in a Bacterial Ribonucleotide Reductase Gene
Bibliographic record
Abstract
A bacterial ribonucleotide reductase gene was found to encode four inteins and three group II introns in the oceanic N2-fixing cyanobacterium Trichodesmium erythraeum. The 13,650-bp ribonucleotide reductase gene is divided into eight extein- or exon-coding sequences that together encode a 768-amino acid mature ribonucleotide reductase protein, with 83% of the gene sequence encoding introns and inteins. The four inteins are encoded on the second half of the gene, and each has conserved sequence motifs for a protein-splicing domain and an endonuclease domain. These four inteins, together with known inteins, define five intein insertion sites in ribonucleotide reductase homologues. Two of the insertion sites are 10 amino acids apart and next to key catalytic residues of the enzyme. Protein-splicing activities of all four inteins were demonstrated in Escherichia coli. The four inteins coexist with three group II introns encoded on the first half of the same gene, which suggests a breakdown of the presumed barrier against intron insertion in this bacterial conserved protein-coding gene.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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) | 0.001 | 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 source (direct Gemma or distilled Codex), 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".