SseK1 and SseK2 Are Novel Translocated Proteins of<i>Salmonella enterica</i>Serovar Typhimurium
Bibliographic record
Abstract
Salmonella enterica is a gram-negative, facultative intracellular pathogen that causes disease symptoms ranging from gastroenteritis to typhoid fever. A key virulence strategy is the translocation of bacterial effector proteins into the host cell, mediated by the type III secretion systems (TTSSs) encoded in Salmonella pathogenicity island 1 (SPI-1) and SPI-2. In S. enterica serovar Typhimurium LT2, we identified the protein products of STM4157 and STM2137 as novel candidate secreted proteins by comparison to known secreted proteins from enterohemorrhagic Escherichia coli and Citrobacter rodentium. The STM4157 and STM2137 proteins, which we have designated SseK1 and SseK2, respectively, are 61% identical at the amino acid level and differ mainly in their N termini. Western analysis showed that in vitro accumulation and secretion of these proteins in serovar Typhimurium were affected by mutations in the two-component systems SsrA/B and PhoP/Q, which are key mediators of intracellular growth and survival. SPI-2 TTSS-dependent translocation of recombinant SseK1::Cya was evident at 9 h postinfection of epithelial cells, while translocation of SseK2::Cya was not detected until 21 h. Remarkably, the translocation signal for SseK1 was contained within the N-terminal 32 amino acids. Fractionation of infected epithelial cells revealed that following translocation SseK1 localizes to the host cytosol, which is unusual among the currently known Salmonella effectors. Phenotypic analysis of DeltasseK1, DeltasseK2, and DeltasseK1/DeltasseK2 mutants provided evidence for a role that was not critical during systemic infection. In summary, this work demonstrates that SseK1 and SseK2 are novel translocated proteins of serovar Typhimurium.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| 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 teacher head, 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".