The Legionella pneumophila Chaperonin – An Unusual Multifunctional Protein in Unusual Locations
Bibliographic record
Abstract
The Legionella pneumophila chaperonin, high temperature protein B (HtpB), was discovered as a highly immunogenic antigen, only a few years after the identification of L. pneumophila as the causative agent of Legionnaires' disease. As its counterparts in other bacterial pathogens, HtpB did not initially receive further attention, particularly because research was focused on a few model chaperonins that were used to demonstrate that chaperonins are essential stress proteins, present in all cellular forms of life and involved in helping other proteins to fold. However, chaperonins have recently attracted increasing interest, particularly after several reports confirmed their multifunctional nature and the presence of multiple chaperonin genes in numerous bacterial species. It is now accepted that bacterial chaperonins are capable of playing a variety of protein folding-independent roles. HtpB is clearly a multifunctional chaperonin that according to its location in the bacterial cell, or in the L. pneumophila-infected cell, plays different roles. HtpB exposed on the bacterial cell surface can act as an invasion factor for non-phagocytic cells, whereas the HtpB released in the host cell can act as an effector capable of altering organelle trafficking, the organization of actin microfilaments and cell signaling pathways. The road to discover the multifunctional nature of HtpB has been exciting and here we provide a historical perspective of the key findings linked to such discovery, as well as a summary of the experimental work (old and new) performed in our laboratory. Our current understanding has led us to propose that HtpB is an ancient protein that L. pneumophila uses as a key molecular tool important to the intracellular establishment of this fascinating pathogen.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| 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".