Characterization of a Novel Fatty Acid-Modifying Pathway in the Biosynthesis of Tambjamine BE-18591 in <i>Streptomyces</i>
Bibliographic record
Abstract
Tambjamines are a class of bacterial bipyrrolic natural products with potent biological activity. Recently, the first actinomycete biosynthetic gene cluster (BGC) responsible for the production of a tambjamine (BE-18591) was discovered in Streptomyces albus, and bioinformatic analysis suggested the alkylamine tail component is constructed using different biosynthetic logic than employed by Proteobacteria to assemble structurally similar tambjamines YP1 and MYP1. Here, we report the experimental characterization of four novel streptomycete proteins and demonstrate that these enable the unique, late-stage assembly of the alkylamine tail of BE-18951. Specifically, a fatty acyl-carrier protein (TabQ) is loaded with a 12-carbon acyl chain, selected for, in part, through the action of an editing type II thioesterase (TabJ). The resulting C 12 –TabQ adduct is then processed to an aldehyde by a novel acyl-ACP reductase (TabE) that harbors none of the telltale amino acid signatures that typically identify these proteins. The resulting aldehyde is finally converted to the amine by an ω-transaminase (TabA) that demonstrates some degree of promiscuity. Our findings highlight the disparate chemical logic employed by Proteo- and Actinobacteria for the biosynthesis of the alkylamine components of tambjamine natural products.
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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 | 0.000 | 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 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".