Gene cloning, structural gene and promoter identification, and active assay of the phosphatidylcholine synthase of <i>Pseudomonas</i> sp. strain 593
Bibliographic record
Abstract
Pseudomonas sp. strain 593, a soil bacterium, is able to use exogenous choline to synthesize phosphatidylcholine via phosphatidylcholine synthase (Pcs). A 2020 bp DNA fragment that hybridized to a Pcs probe was cloned. This fragment contained a large open reading frame (ORF) with two potential ATG start sites that would encode for 293 and 231 amino acid proteins. Fragments containing the two ORFs encoded Pcs when they were inserted into the expression vector pET23a and expressed under the control of the T7 promoter in Escherichia coli BL21(DE3) pLysS. However, when the two ORFs were inserted into the cloning vector pMD18-T and expressed without control of the plasmid promoter in E. coli DH5α, only the larger clone exhibited Pcs activity. This suggested that the larger fragment contained a native promoter driving expression of the smaller ORF. A promoter activity assay, in which DNA fragments were inserted into the promoter-probe plasmid pCB182 and β-galactosidase activity of E. coli transformants was tested, demonstrated that a promoter is indeed present in the DNA region. All results together indicate that the 696 bp ORF, not the larger 897 bp ORF, encodes the Pcs in Pseudomonas sp. strain 593 and carries a promoter in front of its 5' terminus.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".