The <scp>ESX</scp> /type <scp>VII</scp> secretion system modulates development, but not virulence, of the plant pathogen <i> <scp>S</scp> treptomyces scabies </i>
Bibliographic record
Abstract
Streptomyces scabies is a model organism for the investigation of plant-microbe interactions in Gram-positive bacteria. Here, we investigate the type VII protein secretion system (T7SS) in S. scabies; the T7SS is required for the virulence of other Gram-positive bacteria, including Mycobacterium tuberculosis and Staphylococcus aureus. The hallmarks of a functional T7SS are an EccC protein that forms an essential component of the secretion apparatus and two small, sequence-related substrate proteins, EsxA and EsxB. A putative transmembrane protein, EccD, may also be associated with T7S in Actinobacteria. In this study, we constructed strains of the plant pathogen S. scabies carrying marked mutations in genes coding for EccC, EccD, EsxA and EsxB. Unexpectedly, we showed that all four mutant strains retain full virulence towards several plant hosts. However, disruption of the esxA or esxB, but not eccC or eccD, genes affects S. scabies development, including a delay in sporulation, abnormal spore chains and resistance to lysis by the Streptomyces-specific phage ϕC31. We further showed that these phenotypes are specific to the loss of the T7SS substrate proteins EsxA and EsxB, and are not observed when components of the T7SS secretion machinery are lacking. Taken together, these results imply an unexpected intracellular role for EsxA and EsxB.
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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".