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An AAA‐ATPase using an airlock‐like translocation mechanism for folded proteins
Author(s) -
Beckmann Roland
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.00125
Subject(s) - aaa proteins , chromosomal translocation , biophysics , chemistry , transmembrane domain , inner membrane , protein folding , transport protein , microbiology and biotechnology , atpase , membrane , biology , biochemistry , gene , enzyme
Some proteins require completion of folding before translocation across a membrane into another cellular compartment. Yet the permeability barrier of the membrane should not be compromised and mechanisms have remained mostly enigmatic. Here, we present the structure of an AAA‐ATPase of the inner mitochondrial membrane, which facilitates the translocation of a protein, which requires folding and incorporation of a Fe2‐S2 cluster before translocation and subsequent integration into a larger complex. Surprisingly, this AAA‐ATPase assembles into exclusively heptameric homo‐oligomers, with each protomer consisting of an amphipathic transmembrane helix, a middle domain and an ATPase domain. Together, they form two aqueous vestibules, the first accessible from the mitochondrial matrix and the second positioned in the inner membrane, both separated by the seal forming middle domain. Based on this unique architecture, we propose an airlock‐like translocation mechanism employed by this exceptional ATPse.