Mitochondrially encoded methionine is inversely related to longevity in mammals
Bibliographic record
Abstract
Methionine residues in proteins react readily with reactive oxygen species making them particularly sensitive to oxidation. However, because oxidized methionine can be reduced back in a catalyzed reaction, it has been suggested that methionine residues act as oxidant scavengers, protecting not only the proteins where they are located but also the surrounding macromolecules. To investigate whether methionine residues may be selected for or against animal longevity, we carried out a meta-examination of mitochondrial genomes from mammalian species. Our analyses unveiled a hitherto unnoticed observation: mitochondrially encoded polypeptides from short-lived species are enriched in methionine when compared with their long-lived counterparts. We show evidence suggesting that methionine addition to proteins in short-lived species, rather than methionine loss from proteins in long-lived species, is behind the reported difference in methionine usage. The inverse association between longevity and methionine, which persisted after correction for body mass and phylogenetic interdependence, was paralleled by the methionine codon AUA, but not by the codon AUG. Although nuclear encoded mitochondrial polypeptides exhibited higher methionine usage than nonmitochondrial proteins, correlation with longevity was only found within the group of those polypeptides located in the inner mitochondrial membrane. Based on these results, we propose that short-lived animals subjected to higher oxidative stress selectively accumulate methionine in their mitochondrially encoded proteins, which supports the role of oxidative damage in aging.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 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".