RT Journal Article
SR Electronic
T1 Cryo-EM structure of the MgtE Mg<sup>2+</sup> channel pore domain in Mg<sup>2+</sup>-free conditions reveals cytoplasmic pore opening
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.08.27.270991
DO 10.1101/2020.08.27.270991
A1 Fei Jin
A1 Minxuan Sun
A1 Takashi Fujii
A1 Yurika Yamada
A1 Jin Wang
A1 Andrés D. Maturana
A1 Miki Wada
A1 Shichen Su
A1 Jinbiao Ma
A1 Hironori Takeda
A1 Tsukasa Kusakizako
A1 Atsuhiro Tomita
A1 Yoshiko Nakada-Nakura
A1 Kehong Liu
A1 Tomoko Uemura
A1 Yayoi Nomura
A1 Norimichi Nomura
A1 Koichi Ito
A1 Osamu Nureki
A1 Keiichi Namba
A1 So Iwata
A1 Ye Yu
A1 Motoyuki Hattori
YR 2020
UL http://biorxiv.org/content/early/2020/08/28/2020.08.27.270991.abstract
AB MgtE is a Mg2+ channel conserved in organisms ranging from prokaryotes to eukaryotes, including humans, and plays an important role in Mg2+ homeostasis. The previously determined MgtE structures in the Mg2+-bound, closed state and structure-based functional analyses of MgtE revealed that the binding of Mg2+ ions to the MgtE cytoplasmic domain induces channel inactivation to maintain Mg2+ homeostasis. However, due to the lack of a structure of the MgtE channel, including its transmembrane domain in Mg2+-free conditions, the pore-opening mechanism of MgtE has remained unclear.Here, we determined the cryoelectron microscopy (cryo-EM) structure of the MgtE-Fab complex in the absence of Mg2+ ions. The Mg2+-free MgtE transmembrane domain structure and its comparison with the Mg2+-bound, closed-state structure, together with functional analyses, showed the Mg2+-dependent pore opening of MgtE on the cytoplasmic side and revealed the kink motions of the TM2 and TM5 helices at the glycine residues, which are important for channel activity. Overall, our work provides structure-based mechanistic insights into the channel gating of MgtE.Competing Interest StatementThe authors have declared no competing interest.cryo-EMcryoelectron microscopyMgtEMagnesium transporter ESLCSolute carrierCBScystathionine beta synthaseTMtransmembraneFabfragment antigen-bindingFSECfluorescence-detection size-exclusion chromatographyITCisothermal titration calorimetryDDMn-dodecyl-beta-d-maltopyranosideHS-AFMhigh-speed atomic force microscopy