Suggested Role for G4 DNA in Recombinational Switching at the Antigenic Variation Locus of the Lyme Disease Spirochete
Bibliographic record
Abstract
Antigenic variation through targeted DNA rearrangements provides a powerful diversity generating mechanism that allows a variety of pathogens to stay one step ahead of acquired immunity in their hosts. The Lyme disease spirochete encodes such a system that is required for persistent infection. The vls locus, carried on a 29 kb linear plasmid (lp28-1) in the type strain B31, carries 15 silent cassettes from which information is unidirectionally transferred into the expression locus, vlsE. Recent studies have surprisingly shown that, with the exception of the RuvAB branch migrase, no other known recombination/repair proteins appear to play a role in the recombinational switching process. In the work presented here we show that G4 DNA can be formed by sequences within the B31 vlsE locus, prompting us to investigate the presence of potential G4-forming DNA throughout the vls locus of several Lyme spirochete strains and species. We found that runs of G, three nucleotides and longer occur at a very high density, with a greater than 100-fold strand-specific distribution in the vls locus of three B. burgdorferi strains as well as in B. afzelii and B. garinii, in spite of the bias for the use of A-T rich codons in Borrelia species. Our findings suggest the possibility that G4 DNA may be a mediator of recombinational switching at the vlsE locus in the Lyme spirochetes.
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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) | 0.001 | 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 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".