SABATH methyltransferases from white spruce (Picea glauca): gene cloning, functional characterization and structural analysis
Bibliographic record
Abstract
Known members of the plant SABATH family of methyltransferases have important biological functions by methylating hormones, signalling molecules and other metabolites. While all previously characterized SABATH genes were isolated from angiosperms, in this article, we report on the isolation and functional characterization of SABATH genes from white spruce (Picea glauca [Moench] Voss), a gymnosperm. Through EST database search, three genes that encode proteins significantly homologous to known SABATH proteins were identified from white spruce. They were named PgSABATH1, PgSABATH2 and PgSABATH3, respectively. Full length cDNAs of these three genes were cloned and expressed in Escherichia coli. The E. coli-expressed recombinant proteins were tested for methyltransferase activity with a large number of compounds. While no activity was detected for PgSABATH2 and PgSABATH3, PgSABATH1 displayed the highest level of catalytic activity with indole-3-acetic acid (IAA). PgSABATH1 was, therefore, renamed PgIAMT1. Under steady-state conditions, PgIAMT1 exhibited apparent Km values of 18.2 microM for IAA. Homology-based structural modelling of PgIAMT1 revealed that the active site of PgIAMT1 is highly similar to other characterized IAMTs from angiosperms. PgIAMT1 showed expression in multiple tissues, with the highest level of expression detected in embryonic tissues. During somatic embryo maturation, a significant reduction in PgIAMT1 transcript levels was observed when developing cotyledons become apparent which is indicative of mature embryos. The biological roles of white spruce SABATH genes, especially those of PgIAMT1, and the evolution of the SABATH family are discussed.
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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 | 0.000 | 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) | 0.001 | 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 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".