Functional diversification despite structural congruence in the HipBST toxin-antitoxin system of <i>Legionella pneumophila</i>
Bibliographic record
Abstract
ABSTRACT Toxin-antitoxin (TA) systems are abundant genetic modules in bacterial chromosomes and on mobile elements. They are often patchily distributed and their physiological functions remain poorly understood. Here, we characterize a TA system in Legionella pneumophila that is highly conserved across Legionella species. This system is distantly related to Escherichia coli HipBST and we demonstrate that it is a functional tripartite TA system (denoted HipBST Lp ). We identify HipBST Lp homologs in diverse taxa, yet in the Gammaproteobacteria these are almost exclusively found in Legionella species. Notably, the toxin HipT Lp was previously reported to be a pathogenic effector protein that is translocated by L. pneumophila into its eukaryotic hosts. Contrary to this, we find no signal of HipT Lp translocation beyond untranslocated control levels and make several observations consistent with a canonical role as a bacterial toxin. We present structural and biochemical insights into the regulation and neutralization of HipBST Lp , and identify key variations between this system and HipBST Ec . Finally, we show that the target of HipT Lp is likely not conserved with any characterized HipA or HipT toxin. This work serves as a unique comparison of a TA system across bacterial species and illustrates the molecular diversity that exists within a single TA family.
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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".