SopD2 is a Novel Type III Secreted Effector of <i>Salmonella typhimurium</i> That Targets Late Endocytic Compartments Upon Delivery Into Host Cells
Why this work is in the frame
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Bibliographic record
Abstract
Salmonella typhimuriumis a facultative intracellular pathogen that utilizes two type III secretion systems to deliver virulence proteins into host cells. These proteins, termed effectors, alter host cell function to allow invasion into and intracellular survival/replication within a vacuolar compartment. Here we describe SopD2, a novel member of the Salmonella translocated effector (STE) family, which share a conserved N-terminal type III secretion signal. Disruption of the sopD2 gene prolonged the survival of mice infected with a lethal dose of Salmonella typhimurium, demonstrating a significant role for this effector in pathogenesis. Expression of sopD2 was induced inside host cells and was dependent on functional ssrA/B and phoP/Q, two component regulatory systems. HA-tagged SopD2 was delivered into HeLa cells in a SPI-2-dependent manner and associated with both the Salmonella-containing vacuole and with swollen endosomes elsewhere in the cell. Subcellular fractionation confirmed that SopD2 was membrane associated in host cells, while the closely related effector SopD was localized to the cytosol. A SopD2 fusion to GFP associated with small tubular structures and large vesicles containing late endocytic markers, including Rab7. Surprisingly, expression of N-terminal amino acids 1-150 of SopD2 fused to GFP was sufficient to mediate both binding to late endosomes/lysosomes and swelling of these compartments. These findings demonstrate that the N-terminus of SopD2 is a bifunctional domain required for both type III secretion out of Salmonella as well as late endosome/lysosome targeting following translocation into host cells.
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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) | 0.001 | 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 it