Phylogenetic and Structural Analysis of Polyketide Synthases in <i>Aspergilli</i>
Bibliographic record
Abstract
Polyketide synthases (PKSs) of Aspergillus species are multidomain and multifunctional megaenzymes that play an important role in the synthesis of diverse polyketide compounds. Putative PKS protein sequences from Aspergillus species representing medically, agriculturally, and industrially important Aspergillus species were chosen and screened for in silico studies. Six candidate Aspergillus species, Aspergillus fumigatus Af293, Aspergillus flavus NRRL3357, Aspergillus niger CBS 513.88, Aspergillus terreus NIH2624, Aspergillus oryzae RIB40, and Aspergillus clavatus NRRL1, were selected to study the PKS phylogeny. Full-length PKS proteins and only ketosynthase (KS) domain sequence were retrieved for independent phylogenetic analysis from the aforementioned species, and phylogenetic analysis was performed with characterized fungal PKS. This resulted into grouping of Aspergilli PKSs into nonreducing (NR), partially reducing (PR), and highly reducing (HR) PKS enzymes. Eight distinct clades with unique domain arrangements were classified based on homology with functionally characterized PKS enzymes. Conserved motif signatures corresponding to each type of PKS were observed. Three proteins from Protein Data Bank corresponding to NR, PR, and HR type of PKS (XP_002384329.1, XP_753141.2, and XP_001402408.2, respectively) were selected for mapping of conserved motifs on three-dimensional structures of KS domain. Structural variations were found at the active sites on modeled NR, PR, and HR enzymes of Aspergillus. It was observed that the number of iteration cycles was dependent on the size of the cavity in the active site of the PKS enzyme correlating with a type with reducing or NR products, such as pigment, 6MSA, and lovastatin. The current study reports the grouping and classification of PKS proteins of Aspergilli for possible exploration of novel polyketides based on sequence homology; this information can be useful for selection of PKS for polyketide exploration and specific detection of Aspergilli.
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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 | 0.001 |
| Bibliometrics | 0.001 | 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 | 0.000 |
| 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 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".