Native metabolomics identifies pteridines as CutA ligands and modulators of copper binding
Bibliographic record
Abstract
CutA, a conserved protein across all domains of life, has been suggested to be involved in copper tolerance in bacteria, though recent studies have questioned this association, leaving its biological role unknown. To clarify its function, we studied cutA knockout mutants from two phylogenetically distant species, Synechococcus elongatus PCC 7942 and Escherichia coli , using phenotyping combined with metabolomics. To investigate the interaction of CutA with potential substrates and cofactors, we performed a series of native metabolomics experiments with CutA and cell extracts from which we identified the lumazine 2’-deoxyxanthopterin B2, a previously uncharacterized pteridine, to bind CutA in both species. Based on these results, we identified a set of other pteridines, including the essential cofactor tetrahydrobiopterin, as ligands of CutA. In the presence of pterins, we observed an increased affinity of CutA for copper ions. In addition, E. coli CutA mutants exhibited decreased copper resistance. These findings, alongside the known role of pteridines as redox shuttles, suggest a previously unrecognized role for CutA in coordinating cellular copper homeostasis and redox balance via pteridine metabolism.
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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) | 0.000 | 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 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".