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          Institute: MPI für Biochemie     Collection: Cellular Biochemistry (F.-U. Hartl)     Display Documents



ID: 41384.0, MPI für Biochemie / Cellular Biochemistry (F.-U. Hartl)
The protein import motor of mitochondria: a targeted molecular ratchet driving unfolding and translocation
Authors:Okamoto, K.; Brinker, A.; Paschen, S. A.; Moarefi, I.; Hayer-Hartl, M.; Neupert, W.; Brunner, M.
Language:English
Date of Publication (YYYY-MM-DD):2002-07-15
Title of Journal:EMBO Journal
Journal Abbrev.:Embo J.
Volume:21
Issue / Number:14
Start Page:3659
End Page:3671
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:Unfolding and import of preproteins into mitochondria are facilitated by a molecular motor in which heat shock protein 70 (Hsp70) in the matrix plays an essential role. Here we present two different experimental approaches to analyze mechanisms underlying this function of Hsp70. First, preproteins containing stretches of glutamic acid (polyE) or glycine (polyG) repeats in front of folded domains were imported into mitochondria. This occurred although Hsp70 cannot pull on these stretches to unfold the folded domains, since it does not bind to polyE and polyG. Secondly, preproteins containing titin immunoglobulin (Ig)-like domains were imported into mitochondria, despite the fact that forces of >200 pN are required to mechanically unfold these domains. Since molecular motors generate forces of similar to5 pN, Hsp70 could not promote unfolding of the Ig-like domains by mechanical pulling. Our observations suggest that Hsp70 acts as an element of a Brownian ratchet, which mediates unfolding and translocation of preproteins across the mitochondrial membranes.
Free Keywords:Brownian ratchet; Hsp70; mitochondria; protein import; unfolding
Comment of the Author/Creator:Date: 2002, JUL 15
External Publication Status:published
Document Type:Article
Communicated by:N.N.
Affiliations:MPI für Biochemie/Cellular Biochemistry (F.-U. Hartl)/Research Group Hayer-Hartl
External Affiliations:Univ Munich, Inst Physiol Chem, Butenandtstr 5, D-81377 Munich,; Germany; Univ Munich, Inst Physiol Chem, D-81377 Munich, Germany; Biochem Zentrum Heidelberg, D-69120 Heidelberg, Germany
Identifiers:ISI:000176784700011 [ID No:1]
ISSN:0261-4189 [ID No:2]
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