In this manuscript, we show that the structure of a gas phase protein can be determined at near- atomic (2.6 Å) resolution by cryo-EM. To make this possible we developed a workflow with bespoke hardware: native electrospray ion-beam deposition (ESIBD), consisting of native electrospray ionization, mass selection, gentle landing of the protein ions, in-situ ice embedding, and clean cryo- transfer.
we demonstrate the following key points:
We present a 2.6 Å cryo-EM density map of the tetrameric protein complex β-galactosidase. This resolution allows us to determine and analyze structural changes on the side-chain level.
We identify a single dominating gas-phase structure which retains the native secondary and tertiary structure to a high degree.
We observe compaction of the tetrameric complex, due to closing of cavities and grooves upon removal of water.
MD simulations identify dehydration as the main driver of the observed structural changes.