de.mpg.escidoc.pubman.appbase.FacesBean
English
 
Help Guide Disclaimer Contact us Login
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

The protein import motor of mitochondria: a targeted molecular ratchet driving unfolding and translocation

MPS-Authors
http://pubman.mpdl.mpg.de/cone/persons/resource/persons78409

Moarefi,  I.
Hartl, Franz-Ulrich / Cellular Biochemistry, Max Planck Institute of Biochemistry, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons78078

Hayer-Hartl,  M.
Hayer-Hartl, Manajit / Chaperonin-assisted Protein Folding, Max Planck Institute of Biochemistry, Max Planck Society;

Locator
There are no locators available
Fulltext (public)
There are no public fulltexts available
Supplementary Material (public)
There is no public supplementary material available
Citation

Okamoto, K., Brinker, A., Paschen, S. A., Moarefi, I., Hayer-Hartl, M., Neupert, W., et al. (2002). The protein import motor of mitochondria: a targeted molecular ratchet driving unfolding and translocation. EMBO Journal, 21(14), 3659-3671.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0010-6EC0-F
Abstract
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.