Oligomerization Requirements for MX2-Mediated Suppression of HIV-1 Infection
Bibliographic record
Abstract
UNLABELLED: Human myxovirus resistance 2 (MX2/MXB) is an interferon-stimulated gene (ISG) and was recently identified as a late postentry suppressor of human immunodeficiency virus type 1 (HIV-1) infection, inhibiting the nuclear accumulation of viral cDNAs. Although the HIV-1 capsid (CA) protein is believed to be the viral determinant of MX2-mediated inhibition, the precise mechanism of antiviral action remains unclear. The MX family of dynamin-like GTPases also includes MX1/MXA, a well-studied inhibitor of a range of RNA and DNA viruses, including influenza A virus (FLUAV) and hepatitis B virus but not retroviruses. MX1 and MX2 are closely related and share similar domain architectures and structures. However, MX2 possesses an extended N terminus that is essential for antiviral function and confers anti-HIV-1 activity on MX1 [MX1(NMX2)]. Higher-order oligomerization is required for the antiviral activity of MX1 against FLUAV, with current models proposing that MX1 forms ring structures that constrict around viral nucleoprotein complexes. Here, we performed structure-function studies to investigate the requirements for oligomerization of both MX2 and chimeric MX1(NMX2) for the inhibition of HIV-1 infection. The oligomerization state of mutated proteins with amino acid substitutions at multiple putative oligomerization interfaces was assessed using a combination of covalent cross-linking and coimmunoprecipitation. We show that while monomeric MX2 and MX1(NMX2) mutants are not antiviral, higher-order oligomerization does not appear to be required for full antiviral activity of either protein. We propose that lower-order oligomerization of MX2 is sufficient for the effective inhibition of HIV-1. IMPORTANCE: Interferon plays an important role in the control of virus replication during acute infection in vivo. Recently, cultured cell experiments identified human MX2 as a key effector in the interferon-mediated postentry block to HIV-1 infection. MX2 is a member of a family of large dynamin-like GTPases that includes MX1/MXA, a closely related interferon-inducible inhibitor of several viruses, including FLUAV, but not HIV-1. MX GTPases form higher-order oligomeric structures, and the oligomerization of MX1 is required for inhibitory activity against many of its viral targets. Through structure-function studies, we report that monomeric mutants of MX2 do not inhibit HIV-1. However, in contrast to MX1, oligomerization beyond dimer assembly does not seem to be required for the antiviral activity of MX2, implying that fundamental differences exist between the antiviral mechanisms employed by these closely related proteins.
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 | 0.001 |
| 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) | 0.000 | 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".