Protein signatures distinctive of chlamydial species: horizontal transfers of cell wall biosynthesis genes glmU from archaea to chlamydiae and murA between chlamydiae and Streptomyces a aThe GenBank accession numbers for the sequences reported in this paper are indicated in the text.
Bibliographic record
Abstract
Chlamydiae are major human and animal pathogens. Based on alignments of different protein sequences, a number of conserved indels (insertion/deletions) were identified that appear to be unique and distinctive characteristics of the chlamydial species. The identified signatures include one 16 aa and two single aa inserts in the enzyme UDP-N-acetylglucosamine 1-carboxyvinyltransferase (MurA), a 1 aa insert in protein synthesis elongation factor P (EF-P), a 1 aa insert in the Mg(2+) transport protein (MgtE), a 1 aa insert in the carboxy-terminal protease and a 1 aa deletion in the tRNA (guanine-N(1)-)-methyltransferase (TrmD) protein. The homologues of these proteins are found in all major groups of bacteria and the observed indels are present in all available chlamydial sequences but not in any other species (except for the large insert in MurA in Streptomyces). The validity of three of these signatures (MurA, EF-P and MgtE) was tested by PCR amplifying the signature regions from several chlamydial species for which no sequence information was available. All Chlamydiaceae species for which specific fragments could be amplified (Chlamydia suis, Chlamydophila abortus, Chlamydophila psittaci, Chlamydophila felis) contained the expected signatures. Additionally, a fragment of the murA gene from Waddlia chondrophila and the efp gene from Simkania negevensis, two chlamydia-like species, were also cloned and sequenced. The presence of respective indels in these species provides strong evidence that they are specifically related to the traditional chlamydial species, and that these signatures may be distinctive of the entire Chlamydiales order. A 17 aa conserved indel was also identified in the cell wall biosynthesis enzyme UDP-N-acetylglucosamine pyrophosphorylase (GlmU), which is shared by all archaeal and chlamydial homologues. The gene for this protein is indicated to have been horizontally transferred from an archaeon to a common ancestor of the chlamydiae. The results also support a lateral transfer of the murA gene between chlamydiae and STREPTOMYCES: The large inserts in these peptidoglycan synthesis related genes in chlamydiae could account for their unusual cell-wall characteristics. These signatures are also potentially useful for screening of the chlamydiae species.
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".