Modular structure of receptor binding proteins from<i>Lactococcus lactis</i>phages
Bibliographic record
Abstract
Alpha-2,8-linked polysialic acid (polySia) is an important mediator of cellular motility and functional plasticity in the vertebrate brain and has implications in tumor metastasis.PolySia is also a common cell wall modification of pathogenic prokaryotes like Escherichia coli K1 and Neisseria meningitides serogroup B that cause meningitis and severe sepsis in humans.The only known source for enzymes that specifically degrade polySia are E. coli K1 specific bacteriophages.They possess endosialidases as host specificity determining tailspike proteins required to digest the bacterial polySia capsule during infection.We now determined several crystal structures of active site mutants of an endosialidase cloned from bacteriophage K1F (endoNF) in complex with oligomeric sialic acid.The structures have been refined to resolutions up to 1.5 Å.A well defined electron density map of oligomeric sialic acid could be observed for three binding sites, one of which is located in the active site cleft.The complex structure confirms the helical conformation of polySia and supports the model of a substrate assisted catalytic mechanism.
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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 | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".