Extracellular Contractile Injection Systems (eCIS) - Characterization of Conserved Phage Tail-like Structures in Streptomyces
Bibliographic record
Abstract
Extracellular contractile injection systems (eCIS) are bacteriophage tail-like structures produced by bacteria that have been implicated in diverse interactions with eukaryotic cells. Despite their distribution across many bacteria and archaea they have been relatively understudied and are often misclassified as other secretion systems or tailocins. In this work I performed a comprehensive analysis of eCIS across bacterial genomes. I show that all eCIS are comprised of nine core protein families and are closely related to contractile phage tails, a relationship emphasized by the discovery of rare eCIS-like prophages that are the likely evolutionary link between the two. I classify eCIS into six distinct groups and show that group 1 eCIS are ubiquitous in the Streptomyces genus, where their production is linked to the developmental program of these complex filamentous bacteria. The eCIS of Streptomyces coelicolor are natively produced as intracellular phage tail-like structures. Mutations that abrogate eCIS formation cause developmental defects and reduced levels of hyphal cell death at specific times during differentiation that correlate with maximal eCIS production, suggesting a potential role in programmed cell death.
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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 | 0.001 |
| 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".