Abstract 2212 An amphipathic helix drives interaction of Fibrillins with plastoglobule lipid droplets
Bibliographic record
Abstract
Plastoglobule lipid droplets of chloroplasts serve complex roles affecting plant development, stress tolerance and photosynthesis. They harbor a set of approximately 42 proteins that collectively dictate plastoglobule functions. Due to the monolayer structure of plastoglobules which encompass a neutral lipid core, these proteins must associate monotopically on the plastoglobule surface. However, targeting determinants have not been identified for plastoglobule proteins, and the protein-membrane interaction mechanisms that establish the plastoglobule proteome remain unclear. Here, we demonstrate that plastoglobule-localized Fibrillins (FBNs) harbor an amphipathic helix at the lip of their β-barrel that is necessary for proper plastoglobule association. Molecular dynamics simulations support the specific interaction of the amphipathic helix of Arabidopsis thaliana FBN1a with membranes rich in lipid packing defects which are expected to be especially prevalent on the tightly curved surface of plastoglobules. Introduction of one of the amphipathic helices into stromal- or thylakoid-localized FBNs was ineffective at redirecting the proteins to plastoglobules, likely due to endogenous protein-protein interactions that override the influence of the amphipathic helix. Proteomic analyses indicate AtFBN1a influences the plastoglobule proteome through outcompeting and recruiting specific proteins. We also demonstrate that the plastoglobule-localized FBNs, AtFBN1a and AtFBN7a, bind unsaturated fatty acids, particularly C18:1, and that elimination of the amphipathic helix suppresses fatty acid binding in AtFBN1a, but promotes fatty acid binding in AtFBN7a. Predicted amphipathic helices can be identified on two-thirds of plastoglobule proteins, indicating the use of amphipathic helices may be a general mechanism by which proteins selectively associate with plastoglobules. This work was supported by a grant from the National Science Foundation (MCB-2034631) to P.K.L. This work used Delta at NCSA through allocation BIO210061 from the Advanced Cyberinfrastructure Coordination Ecosystem Services & Supported (ACCESS) program, which is supported by National Science Foundation grants #2138259, #2138286. #2138307, #2137603, and #2138296.
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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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".