Structural and Mutational Analysis of the SBDS Protein Family
Bibliographic record
Abstract
Shwachman-Diamond Syndrome (SDS) is an autosomal recessive disorder characterized by bone marrow failure with significant predisposition to the development of poor prognosis myelodysplasia and leukemia, exocrine pancreatic failure and metaphyseal chondrodysplasia. Although the SBDS gene mutated in this disorder is highly conserved in Archaea and all eukaryotes, the function is unknown. To interpret the molecular consequences of SDS-associated mutations, we have solved the crystal structure of the Archaeoglobus fulgidus SBDS protein orthologue at a resolution of 1.9 angstroms, revealing a three domain architecture. The N-terminal (FYSH) domain is the most frequent target for disease mutations and contains a novel mixed alpha/beta-fold identical to the single domain yeast protein Yhr087wp that is implicated in RNA metabolism. The central domain consists of a three-helical bundle, whereas the C-terminal domain has a ferredoxin-like fold. By genetic complementation analysis of the essential Saccharomyces cerevisiae SBDS orthologue YLR022C, we demonstrate an essential role in vivo for the FYSH domain and the central three-helical bundle. We further show that the common SDS-related K62X truncation is non-functional. Most SDS-related missense mutations that alter surface epitopes do not impair YLR022C function, but mutations affecting residues buried in the hydrophobic core of the FYSH domain severely impair or abrogate complementation. These data are consistent with absence of homozygosity for the common K62X truncation mutation in individuals with SDS, indicating that the SDS disease phenotype is a consequence of expression of hypomorphic SBDS alleles and that complete loss of SBDS function is likely to be lethal.
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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) | 0.001 | 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".