Circular Dichroism Spectra and Electrophoretic Mobility Shift Assays Show That Human Replication Protein A Binds and Melts Intramolecular G-Quadruplex Structures<sup>,</sup>
Bibliographic record
Abstract
Noncanonical DNA structures such as G-quadruplexes might obstruct the binding of hRPA, compromising the accuracy of replication, and be a source of genomic instability. In this study, circular dichroism (CD) and electrophoretic mobility shift assay (EMSA) experiments were used to show that hRPA can bind and melt nontelomeric, intramolecular DNA G-quadruplexes under physiologically germane conditions. EMSA results show that hRPA binds to a 58-mer that includes an embedded quadruplex with an affinity equal to or greater than to nonquadruplex forming 58-mers. Moreover, hRPA binds to a 26-mer purine-rich quadruplex-forming sequence with an affinity indistinguishable from that for binding to the complementary pyrimidine-rich sequence. Under the same conditions, hRPA does not have significant affinity for binding to the duplex formed from the two sequences. Thus, DNA secondary structures can significantly modulate the binding affinity of hRPA over and above its known preference for pyrimidine-rich single-stranded sequences, so that at least some intramolecular G-quadruplex structures may not inhibit hRPA binding during DNA replication. CD spectral changes in combination with EMSA titrations suggest that one hRPA heterotrimer is sufficient to form a stable complex with an unfolded 26-mer G-quadruplex prior to the binding of a second hRPA molecule.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.001 | 0.000 |
| 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".