Development and Characterization of a Xylose-Dependent System for Expression of Cloned Genes in <i>Bacillus subtilis</i> : Conditional Complementation of a Teichoic Acid Mutant
Bibliographic record
Abstract
We have developed a xylose-dependent expression system for tight and modulated expression of cloned genes in Bacillus subtilis. The expression system is contained on plasmid pSWEET for integration at the amyE locus of B. subtilis and incorporates components of the well-characterized, divergently transcribed xylose utilization operon. The system contains the xylose repressor encoded by xylR, the promoter and 5' portion of xylA containing an optimized catabolite-responsive element, and intergenic xyl operator sequences. We have rigorously compared this expression system to the isopropyl-beta-D-thiogalactopyranoside-induced spac system using a thermostable beta-galactosidase reporter (BgaB) and found the xyl promoter-operator to have a greater capacity for modulated expression, a higher induction/repression ratio (279-fold for the xyl system versus 24-fold with the spac promoter), and lower levels of expression in the absence of an inducer. We have used this system to probe an essential function in wall teichoic acid biosynthesis in B. subtilis. Expression of the teichoic acid biosynthesis gene tagD, encoding glycerol-3-phosphate cytidylyltransferase, from the xylose-based expression system integrated at amyE exhibited xylose-dependent complementation of the temperature-sensitive mutant tag-12 when grown at the nonpermissive temperature. Plasmid pSWEET thus provides a robust new expression system for conditional complementation in B. subtilis.
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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".