title: Cyclophilin 20 is involved in mitochondrial protein folding in cooperation with molecular chaperones Hsp70 and Hsp60.
abstract: We studied the role of mitochondrial cyclophilin 20 (CyP20), a peptidyl-prolyl cis-trans isomerase, in preprotein translocation across the mitochondrial membranes and protein folding inside the organelle. The inhibitory drug cyclosporin A did not impair membrane translocation of preproteins, but it delayed the folding of an imported protein in wild-type mitochondria. Similarly, Neurospora crassa mitochondria lacking CyP20 efficiently imported preproteins into the matrix, but folding of an imported protein was significantly delayed, indicating that CyP20 is involved in protein folding in the matrix. The slow folding in the mutant mitochondria was not inhibited by cyclosporin A. Folding intermediates of precursor molecules reversibly accumulated at the molecular chaperones Hsp70 and Hsp60 in the matrix. We conclude that CyP20 is a component of the mitochondrial protein folding machinery and that it cooperates with Hsp70 and Hsp60. It is speculated that peptidyl-prolyl cis-trans isomerases in other cellular compartments may similarly promote protein folding in cooperation with chaperone proteins.
authors.affiliation: Biochemisches Institut, Universität Freiburg, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Rassow
authors.forename: K
authors.initials: K
authors.lastname: Mohrs
authors.forename: S
authors.initials: S
authors.lastname: Koidl
authors.forename: I B
authors.initials: IB
authors.lastname: Barthelmess
authors.forename: N
authors.initials: N
authors.lastname: Pfanner
authors.forename: M
authors.initials: M
authors.lastname: Tropschug
mesh_terms: D000591:Amino Acid Isomerases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D018834:Chaperonin 60 / Q000378:metabolism*; D018833:Chaperonins / Q000378:metabolism*; D017931:DNA Primers / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism; D005800:Genes, Fungal; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D009154:Mutation; D009492:Neurospora crassa / Q000235:genetics / Q000378:metabolism; D019696:Peptidylprolyl Isomerase; D017510:Protein Folding; D013762:Tetrahydrofolate Dehydrogenase / Q000737:chemistry / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D018834:Chaperonin 60; D017931:DNA Primers; D004271:DNA, Fungal; D004792:Enzyme Precursors; D018840:HSP70 Heat-Shock Proteins; D013762:Tetrahydrofolate Dehydrogenase; D018833:Chaperonins; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase