Abstract
Translocation of mitochondrial precursor proteins across the mitochondrial outer membrane is facilitated by the translocase of the outer membrane (TOM) complex. By using site-specific photocrosslinking, we have mapped interactions between TOM proteins and a mitochondrial precursor protein arrested at two distinct stages, stage A (accumulated at 0°C) and stage B (accumulated at 30°C), in the translocation across the outer membrane at high resolution not achieved previously. Although the stage A and stage B intermediates were assigned previously to the forms bound to the cis site and the trans site of the TOM complex, respectively, the results of crosslinking indicate that the presequence of the intermediates at both stage A and stage B is already on the trans side of the outer membrane. The mature domain is unfolded and bound to Tom40 at stage B whereas it remains folded at stage A. After dissociation from the TOM complex, translocation of the stage B intermediate, but not of the stage A intermediate, across the inner membrane was promoted by the intermembrane-space domain of Tom22. We propose a new model for protein translocation across the outer membrane, where translocation of the presequence and unfolding of the mature domain are not necessarily coupled.
| Original language | English |
|---|---|
| Pages (from-to) | 3634-3639 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 96 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - 1999 Mar 30 |
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Uncoupling of transfer of the presequence and unfolding of the mature domain in precursor translocation across the mitochondrial outer membrane. / Kanamori, Takashi; Nishikawa, Shuh Ichi; Nakai, Masato; Shin, Injae; Schultz, Peter G.; Endo, Toshiya.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 96, No. 7, 30.03.1999, p. 3634-3639.Research output: Contribution to journal › Article
TY - JOUR
T1 - Uncoupling of transfer of the presequence and unfolding of the mature domain in precursor translocation across the mitochondrial outer membrane
AU - Kanamori, Takashi
AU - Nishikawa, Shuh Ichi
AU - Nakai, Masato
AU - Shin, Injae
AU - Schultz, Peter G.
AU - Endo, Toshiya
PY - 1999/3/30
Y1 - 1999/3/30
N2 - Translocation of mitochondrial precursor proteins across the mitochondrial outer membrane is facilitated by the translocase of the outer membrane (TOM) complex. By using site-specific photocrosslinking, we have mapped interactions between TOM proteins and a mitochondrial precursor protein arrested at two distinct stages, stage A (accumulated at 0°C) and stage B (accumulated at 30°C), in the translocation across the outer membrane at high resolution not achieved previously. Although the stage A and stage B intermediates were assigned previously to the forms bound to the cis site and the trans site of the TOM complex, respectively, the results of crosslinking indicate that the presequence of the intermediates at both stage A and stage B is already on the trans side of the outer membrane. The mature domain is unfolded and bound to Tom40 at stage B whereas it remains folded at stage A. After dissociation from the TOM complex, translocation of the stage B intermediate, but not of the stage A intermediate, across the inner membrane was promoted by the intermembrane-space domain of Tom22. We propose a new model for protein translocation across the outer membrane, where translocation of the presequence and unfolding of the mature domain are not necessarily coupled.
AB - Translocation of mitochondrial precursor proteins across the mitochondrial outer membrane is facilitated by the translocase of the outer membrane (TOM) complex. By using site-specific photocrosslinking, we have mapped interactions between TOM proteins and a mitochondrial precursor protein arrested at two distinct stages, stage A (accumulated at 0°C) and stage B (accumulated at 30°C), in the translocation across the outer membrane at high resolution not achieved previously. Although the stage A and stage B intermediates were assigned previously to the forms bound to the cis site and the trans site of the TOM complex, respectively, the results of crosslinking indicate that the presequence of the intermediates at both stage A and stage B is already on the trans side of the outer membrane. The mature domain is unfolded and bound to Tom40 at stage B whereas it remains folded at stage A. After dissociation from the TOM complex, translocation of the stage B intermediate, but not of the stage A intermediate, across the inner membrane was promoted by the intermembrane-space domain of Tom22. We propose a new model for protein translocation across the outer membrane, where translocation of the presequence and unfolding of the mature domain are not necessarily coupled.
UR - http://www.scopus.com/inward/record.url?scp=0033616726&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0033616726&partnerID=8YFLogxK
U2 - 10.1073/pnas.96.7.3634
DO - 10.1073/pnas.96.7.3634
M3 - Article
C2 - 10097089
AN - SCOPUS:0033616726
VL - 96
SP - 3634
EP - 3639
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
SN - 0027-8424
IS - 7
ER -