title: The structural plasticity of Tom71 for mitochondrial precursor translocations.
abstract: Mitochondrial precursors are transported through the translocase of the outer membrane (TOM) complex. Tom70/Tom71 is a major surface receptor of the TOM complex for mitochondrial precursors and facilitates Hsp70/Hsp90-escorted precursor translocation into the mitochondrion. Previous structural studies of Tom71 have revealed that it contains an N-terminal and a C-terminal domain and that the two domains may remain in an open conformation when binding to Hsp70/Hsp90. In a newly obtained crystal form of a complex of Tom71 and the Hsp70 C-terminus, the N-terminal domain was found to have rotated about 12 degrees towards the C-terminal domain compared with the previous determined crystal structure of Tom71 in the open conformation. This newly solved structure is defined as the ;intermediate conformation'. The domain rearrangements in Tom71 significantly change the surface hydrophobicity and the volume of the precursor-binding pocket. This work suggests that Tom70/Tom71-family members may exhibit structural plasticity from the intermediate conformation to the fully open conformation when complexed with Hsp70/Hsp90. This structural plasticity enables the precursor receptors to accommodate different precursor substrates for mitochondrial translocation.
authors.affiliation: Department of Cell Biology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
authors.forename: Jingzhi
authors.initials: J
authors.lastname: Li
authors.forename: Wenjun
authors.initials: W
authors.lastname: Cui
authors.forename: Bingdong
authors.initials: B
authors.lastname: Sha
mesh_terms: D018360:Crystallography, X-Ray; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D008928:Mitochondria / Q000737:chemistry* / Q000378:metabolism; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D008953:Models, Anatomic; D008958:Models, Molecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000737:chemistry* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D018840:HSP70 Heat-Shock Proteins; D033681:Mitochondrial Membrane Transport Proteins; C090869:SSA3 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; C099144:TOM71 protein, S cerevisiae
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