T361I
Category 3/4 — Most DruggablePathogenic/Likely pathogenicTransmembrane · predictedEditorialThreonine → Isoleucine at position 361 in a connecting loop between transmembrane helices. ClinVar Pathogenic/Likely pathogenic with the full WFS1 clinical spectrum documented. AlphaMissense 0.995 (near-maximum pathogenic signal), DynaMut2 ΔΔG +1.28 kcal/mol — a strongly STABILIZING substitution. The most striking ΔΔG-pathogenicity disconnect in this batch.
Interactive 3D Structure
Bond changes · DynaMut2 interaction analysis
| Interaction type | Wild-type partner | Mutant partner | Status |
|---|---|---|---|
| Hydrogen bond | M357 | M357 | Preserved |
| Hydrogen bond | V358 | V358 | Preserved |
| Hydrogen bond | V364 | V364 | Preserved |
| Hydrogen bond | F365 | F365 | Preserved |
| Polar contact | M357 | M357 | Preserved |
| Polar contact | V358 | V358 | Preserved |
| Polar contact | I359 | I359 | Preserved |
| Polar contact | K363 | K363 | Preserved |
| Polar contact | V364 | V364 | Preserved |
| Polar contact | F365 | F365 | Preserved |
| Van der Waals | M357 | — | Lost |
| Van der Waals | I359 | I359 | Preserved |
| Van der Waals | — | F408 | Gained |
| Hydrophobic | — | F365 | Gained |
| Hydrophobic | F408 | F408 | Preserved |
| Hydrophobic | — | F439 | Gained |
| Hydrophobic | V536 | V536 | Preserved |
| Hydrophobic | W540 | W540 | Preserved |
Lost / gained / preserved interatomic contacts at the variant residue, from the DynaMut2 (Arpeggio) interaction analysis of the wild-type and energy-minimized mutant structures.
Computational Predictions
Clinical Evidence
Observed at very low frequency in gnomAD.
Structural Context
Position 361 sits in a connecting loop region of wolframin. The AlphaFold model places T361 within 5 Å of LEU362 (2.5 Å), CYS360 (2.5 Å), VAL358 (3.8 Å), MET357 (3.9 Å), VAL364 (4.2 Å), and LYS363 (4.2 Å). The local environment is predominantly hydrophobic with a single nearby cysteine (C360) and a lysine (K363). The wild-type threonine sits in this environment with its small polar hydroxyl providing a hydrogen-bonding capacity that connects to either nearby backbone amides or to the K363 side chain.
Replacing threonine with isoleucine here is unusually stabilizing — DynaMut2 returns ΔΔG = +1.28 kcal/mol, meaning the variant fold is significantly tighter than wild-type. The structural reasoning: isoleucine is a larger, branched hydrophobic residue that fits better into the surrounding hydrophobic cluster (V358, M357, V364) than threonine's polar hydroxyl did. The polar contact with K363 is lost, but the hydrophobic packing gain dominates.
And yet the variant is pathogenic — AlphaMissense 0.995, near-maximum — and clinically validated with the full WFS1 spectrum (Wolfram syndrome 1, Wolfram-like syndrome, DFNA6 hearing loss, type 2 diabetes, cataract 41). The pathogenicity cannot be explained by fold instability. The mechanism must be functional.
Three plausible functional mechanisms: first, the lost T361 hydroxyl participated in a specific intramolecular hydrogen bond or partner-protein contact that the larger I361 cannot recapitulate; second, the increased local rigidity from improved hydrophobic packing eliminates a conformational flexibility that wolframin requires for function (e.g., during ER-to-membrane trafficking or partner binding); third, the loop's role as a recognition surface for a binding partner depends on the precise threonine geometry, and isoleucine cannot substitute.
The Atlas's neighbor analysis surfaces the K363 contact (4.2 Å) — that's a potential hydrogen-bond partner the wild-type threonine made and the mutant isoleucine cannot. This is plausibly the broken contact that drives pathogenicity, even though the fold is more stable overall.
Druggability Assessment
The mechanism is functional rather than structural: the lost T361 hydroxyl made a specific contact (most likely H-bonding to K363 at 4.2 Å) that the mutant isoleucine cannot recapitulate, and the loop's role as a recognition surface or conformational hinge is compromised by the increased rigidity.
Therapeutic strategy: site-directed small-molecule design that occupies the K363 hydrogen-bond niche the wild-type threonine maintained. Alternative: a chaperone that biases the loop toward its wild-type, slightly-less-stable conformation.
Why this matters
Feed this card to Wolfram Intelligence
Download the T361I PDF below and upload it to Wolfram Intelligence to generate therapeutic-strategy proposals — guanidinium mimetics, sigma-1 agonist docking, NAC thiol-capping. NAC is already on the bench-testing list.