A Single Amino Acid Substitution in Herpes Simplex Virus Type 1 VP16 Inhibits Binding to the Virion Host Shutoff Protein and Is Incompatible with Virus Growth
Bibliographic record
Abstract
In addition to its well-established role in the activation of herpes simplex virus immediate-early gene transcription, VP16 interacts with and downregulates the function of the virion host shutoff protein (vhs), thereby attenuating vhs-mediated destruction of viral mRNAs and translational arrest at late times of infection. We have carried out two-hybrid analysis in vivo and protein-protein interaction assays in vitro to identify determinants in VP16 necessary for interaction with vhs. The minimal amino-terminal subfragment of VP16 capable of binding to vhs encompassed residues 1 to 345. Alteration of a single leucine at position 344 to alanine (L344A) in the context of the amino-terminal fragment of VP16 containing residues 1 to 404 was sufficient to abolish interaction with vhs in vitro and in vivo. Leu344 could be replaced with hydrophobic amino acids (Ile, Phe, Met, or Val) but not by Asn, Lys, or Pro, indicating that hydrophobicity is an important property of binding to vhs. VP16 harboring a loss-of-function mutation at L344 was not compromised in its ability to interact with host cell factor (HCF-1) or to activate transcription of viral immediate-early genes in transient-transfection assays. Virus complementation assays using the VP16-null virus 8MA and the VP16/vhs double-mutant virus 8MAdeltaSma showed that VP16(L344A) was able to complement the growth of 8MAdeltaSma but not 8MA. Thus, a single point mutation in VP16 uncouples binding to vhs from other functions of VP16 required for virus growth and indicates that direct physical association between VP16 and vhs is necessary to sustain a productive infection.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".