Time-resolved serial femtosecond crystallography reveals early structural changes in channelrhodopsin

X線自由電子レーザーを用いて、光照射によるチャネルロドプシンの構造変化の過程を捉えることに成功. 京都大学プレスリリース. 2021-03-26.Channelrhodopsins (ChRs) are microbial light-gated ion channels utilized in optogenetics to control neural activity with light . Light absorption causes retinal chromophore isomerization and subsequent protein conformational changes visualized as optically distinguished intermediates, coupled with channel opening and closing. However, the detailed molecular events underlying channel gating remain unknown. We performed time-resolved serial femtosecond crystallographic analyses of ChR by using an X-ray free electron laser, which revealed conformational changes following photoactivation. The isomerized retinal adopts a twisted conformation and shifts toward the putative internal proton donor residues, consequently inducing an outward shift of TM3, as well as a local deformation in TM7. These early conformational changes in the pore-forming helices should be the triggers that lead to opening of the ion conducting pore

Raw diffraction images of eukaryotic MATE transporter (AtDTX14)

Multidrug And Toxic compound Extrusion (MATE) transporter exports xenobiotics by using the gradient of H+. The crystals were obtained within the lipidic cubic phase. 288+85 (Auto+manual) small-wedge (5-20°/crystal) datasets collected from loop-harvested microcrystals using MX225HS CCD detector at a wavelength of 1 Å on BL32XU, SPring-8. The crystals belonged to space group P212121 with unit cell parameters a=52.8, b=86.8, c=116.4 Å. 100 datasets were merged at 2.6 Å resolution in the published result (Miyauchi et al. Nature Communications, 2017; PDB code: 5Y50) using KAMO; see processing note https://github.com/keitaroyam/yamtbx/wiki/Processing-AtDTX14-data-(5Y50) Note that most frames have lipid rings

Systolic blood pressure and cardiac mortality related to serum total bilirubin levels at admission in patients with acute heart failure

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Cryo-EM structure of the human MT1–Gi signaling complex

Melatonin receptors (MT1 and MT2) transduce inhibitory signaling by melatonin (N-acetyl-5-methoxytryptamine), which is associated with sleep induction and circadian rhythm modulation. Although recently reported crystal structures of ligand-bound MT1 and MT2 elucidated the basis of ligand entry and recognition, the ligand-induced MT1 rearrangement leading to Gi-coupling remains unclear. Here we report a cryo-EM structure of the human MT1–Gi signaling complex at 3.3 Å resolution, revealing melatonin-induced conformational changes propagated to the G-protein-coupling interface during activation. In contrast to other Gi-coupled receptors, MT1 exhibits a large outward movement of TM6, which is considered a specific feature of Gs-coupled receptors. Structural comparison of Gi and Gs complexes demonstrated conformational diversity of the C-terminal entry of the Gi protein, suggesting loose and variable interactions at the end of the α5 helix of Gi protein. These notions, together with our biochemical and computational analyses, highlight variable binding modes of Gαi and provide the basis for the selectivity of G-protein signaling. © 2021, The Author(s), under exclusive licence to Springer Nature America, Inc