PMID: 27490483
Demircioglu FE, Sosa BA, Ingram J, Ploegh HL, Schwartz TU
Structures of TorsinA and its disease-mutant complexed with an activator reveal the molecular basis for primary dystonia.
Elife. 2016 Aug 4;5. pii: e17983. doi: 10.7554/eLife.17983.
The most common cause of early onset primary dystonia, a neuromuscular disease, is a glutamate deletion (DeltaE) at position 302/303 of TorsinA, a AAA+ ATPase that resides in the endoplasmic reticulum. While the function of TorsinA remains elusive, the DeltaE mutation is known to diminish binding of two TorsinA ATPase activators: lamina-associated protein 1 (LAP1) and its paralog, luminal domain like LAP1 (LULL1). Using a nanobody as a crystallization chaperone, we obtained a 1.4 A crystal structure of human TorsinA in complex with LULL1. This nanobody likewise stabilized the weakened TorsinADeltaE-LULL1 interaction, which enabled us to solve its structure at 1.4 A also. A comparison of these structures shows, in atomic detail, the subtle differences in activator interactions that separate the healthy from the diseased state. This information may provide a structural platform for drug development, as a small molecule that rescues TorsinADeltaE could serve as a cure for primary dystonia.