Download MendeleyGlutathione binding to the plant At Atm3 transporter and implications for the conformational coupling of ABC transporters.
Fan, C., Rees, D.C.(2022) Elife 11
- PubMed: 35333177
- DOI: https://doi.org/10.7554/eLife.76140
- Primary Citation of Related Structures:
7N58, 7N59, 7N5A, 7N5B - PubMed Abstract:
The ATP binding cassette (ABC) transporter of mitochondria (Atm) from Arabidopsis thaliana ( At Atm3) has been implicated in the maturation of cytosolic iron-sulfur proteins and heavy metal detoxification, plausibly by exporting glutathione derivatives. Using single-particle cryo-electron microscopy, we have determined four structures of At Atm3 in three different conformational states: two inward-facing conformations (with and without bound oxidized glutathione [GSSG]), together with closed and outward-facing states stabilized by MgADP-VO 4 . These structures not only provide a structural framework for defining the alternating access transport cycle, but also reveal the paucity of cysteine residues in the glutathione binding site that could potentially form inhibitory mixed disulfides with GSSG. Despite extensive efforts, we were unable to prepare the ternary complex of At Atm3 containing both GSSG and MgATP. A survey of structurally characterized type IV ABC transporters that includes At Atm3 establishes that while nucleotides are found associated with all conformational states, they are effectively required to stabilize occluded, closed, and outward-facing conformations. In contrast, transport substrates have only been observed associated with inward-facing conformations. The absence of structures with dimerized nucleotide binding domains containing both nucleotide and transport substrate suggests that this form of the ternary complex exists only transiently during the transport cycle.
Organizational Affiliation:
Division of Chemistry and Chemical Engineering, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, United States.
