Test Your Hypothesis

 BGPT Odds of True

The hypothesis asks whether the Glu505 clamp model survives three specific tests. E505D supports it (moderate evidence); E505Q and CTT-truncation tests are absent from the supplied evidence, so overall likelihood is capped near a coin-flip weighted toward survival.

 Hypothesis Novelty

The Glu505 clamp concept is new to the 2026 HDX-MS study; framing its falsification via conservative/neutral mutations and CTT truncation is a specific, testable refinement of very recent work.

 Quick Analysis Plan Copied

 Long Analysis Plan

Evidence actually available

The supplied primary study tested only E505D. No E505Q variant or CTT-truncation construct was measured by HDX-MS in the provided records, so the hypothesis as posed cannot be fully adjudicated — two of its three tests are missing entirely. What the data do show is a conservative-mutation result consistent with the clamp model:

Photochemistry: After 20 min blue-light illumination at 10 °C, WT ClCRY4 reaches near-complete FADox depletion, whereas E505D retains roughly 40% of FADox and its FADH• signaling-state plateau reaches only ~50-60% of the WT level (E505D photochemistry defect).

HDX-MS: Pump-probe HDX-MS shows the WT light-induced protection across seven peptides is largely abolished in E505D, with the notable exception of the α22-helix peptide 482-495, which retains a WT-like response (E505D HDX protection loss). This differential rescue of 482-495 is the most interesting nuance: it suggests Glu505 is required for propagating light-induced protection beyond the immediate CTT-contacting helix, partially constraining what the "clamp" can be doing structurally.

Critical evaluation and what is missing

• E505D evidence is supportive but partial. Two biological replicates, in vitro purified protein, temporal resolution limited to >10 s, and no magnetic-field or in vivo validation are all stated or inferred limitations (Study limitations).
• E505Q and CTT-truncation are untested here. The clamp model predicts charge-neutralization (E505Q) should phenocopy E505D, and CTT truncation should constitutively mimic the light-protected state. Neither dataset exists in the supplied records — these remain the decisive missing tests.
• Falsification criterion (paper-inferred): if a properly folded E505D variant showed WT FADH• accumulation and full light-induced HDX protection in all seven peptides, the clamp model would be weakened (Falsification criterion). The observed data do not meet this criterion, so the model survives E505D.

Verdict: The Glu505 clamp model survives the E505D test at moderate confidence, but it is untested by E505Q and CTT-truncation in the supplied evidence. The E505D defect could also arise from indirect destabilization of the FAD pocket rather than a specific clamp interaction — only E505Q/CTT-truncation data (or structural methods) can discriminate.