3.A.1.210.11
Inner membrane miltochondrial-like homodimeric Atm1 of 608 aas and 6 TMSs per subunit.  The structure has been solved to 2.4 Å resolution (Lee et al. 2014).  It is required for the formation of cytosolic iron-sulfur cluster-containing proteins (Lill et al. 2012); but see also, 3.A.210.15. It exports glutathione derivatives and confers protection against heavy-metal toxicity. Fan et al. 2020 determined eight structures by X-ray crystallography and single-particle cryo-electron microscopy in distinct conformational states, stabilized by individual disulfide crosslinks and nucleotides. As NaAtm1 progresses through the transport cycle, conformational changes in TMS 6 alter the glutathione-binding site and the associated substrate-binding cavity. Kinking of TMS 6 in the post-ATP hydrolysis state, stabilized by MgADPVO4, eliminates this cavity, precluding uptake of glutathione derivatives. The presence of this cavity during the transition from the inward-facing to outward-facing conformational states, and its absence in the reverse direction, provide a mechanism for enforcing the export directionality of transport by NaAtm1 (Fan et al. 2020).