Molecular signatures in protein sequences that are characteristic of cyanobacteria and plastid homologues
Bibliographic record
Abstract
Fourteen conserved indels (i.e. inserts or deletions) have been identified in 10 widely distributed proteins that appear to be characteristic of cyanobacterial species and are not found in any other group of bacteria. These signatures include three inserts of 6, 7 and 28 aa in the DNA helicase II (UvrD) protein, an 18-21 aa insert in DNA polymerase I, a 14 aa insert in the enzyme ADP-glucose pyrophosphorylase, a 3 aa insert in the FtsH protein, an 11-13 aa insert in phytoene synthase, a 5 aa insert in elongation factor-Tu, two deletions of 2 and 7 aa in ribosomal S1 protein, a 2 aa insert in the SecA protein, a 1 aa deletion and a 6 aa insert in the enzyme inosine-5'-monophosphate dehydrogenase and a 1 aa deletion in the major sigma factor. These signatures, which are flanked by conserved regions, provide molecular markers for distinguishing cyanobacterial taxa from all other bacteria and they should prove helpful in the identification of cyanobacterial species, simply on the basis of the presence or absence of these markers in the corresponding proteins. The signatures in six of these proteins (SecA, elongation factor-Tu, ADP-glucose pyrophosphorylase, phytoene synthase, FtsH and ribosomal S1 protein) are also commonly present in plastid homologues from plants and algae (chlorophytes, chromophytes and rhodophytes), indicating their specific relationship to cyanobacteria and supporting their endosymbiotic origin from these bacteria. In phylogenetic trees based on a number of these proteins (SecA, UvrD, DNA polymerase I, elongation factor-Tu) that were investigated, the available cyanobacterial homologues grouped together with high affinity (>95 % bootstrap value), supporting the view that the cyanobacterial phylum is monophyletic and that the identified signatures were introduced in a common ancestor of this group.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| 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 | 0.001 |
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".