Abstract
A rotary motor F1, a catalytic part of ATP synthase, makes a 120° step rotation driven by hydrolysis of one ATP, which consists of 80° and 40° substeps initiated by ATP binding and probably by ADP and/or Pi dissociation, respectively. During active rotations, F 1 spontaneously fails in ADP release and pauses after a 80° substep, which is called the ADP-inhibited form. In the present work, we found that, when pushed >+40° with magnetic tweezers, the pausing F1 resumes its active rotation after releasing inhibitory ADP. The rate constant of the mechanical activation exponentially increased with the pushed angle, implying that F1 weakens the affinity of its catalytic site for ADP as the angle goes forward. This finding explains not only its unidirectional nature of rotation, but also its physiological function in ATP synthesis; it would readily bind ADP from solution when rotated backward by an Fo motor in the ATP synthase. Furthermore, the mechanical work for the forced rotation was efficiently converted into work for expelling ADP from the catalytic site, supporting the tight coupling between the rotation and catalytic event.
| Original language | English |
|---|---|
| Pages (from-to) | 4288-4293 |
| Number of pages | 6 |
| Journal | Proceedings of the National Academy of Sciences of the United States of America |
| Volume | 102 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - 2005 Mar 22 |
| Externally published | Yes |
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Keywords
- ADP inhibition
- ATP synthase
- F1-ATPase
- Magnetic tweezers
- Single-molecule observation
ASJC Scopus subject areas
- Genetics
- General
Cite this
Activation of pausing F1 motor by external force. / Hirono-Hara, Yoko; Ishizuka, Koji; Kinosita, Kasuhiko; Yoshida, Masasuke; Noji, Hiroyuki.
In: Proceedings of the National Academy of Sciences of the United States of America, Vol. 102, No. 12, 22.03.2005, p. 4288-4293.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Activation of pausing F1 motor by external force
AU - Hirono-Hara, Yoko
AU - Ishizuka, Koji
AU - Kinosita, Kasuhiko
AU - Yoshida, Masasuke
AU - Noji, Hiroyuki
PY - 2005/3/22
Y1 - 2005/3/22
N2 - A rotary motor F1, a catalytic part of ATP synthase, makes a 120° step rotation driven by hydrolysis of one ATP, which consists of 80° and 40° substeps initiated by ATP binding and probably by ADP and/or Pi dissociation, respectively. During active rotations, F 1 spontaneously fails in ADP release and pauses after a 80° substep, which is called the ADP-inhibited form. In the present work, we found that, when pushed >+40° with magnetic tweezers, the pausing F1 resumes its active rotation after releasing inhibitory ADP. The rate constant of the mechanical activation exponentially increased with the pushed angle, implying that F1 weakens the affinity of its catalytic site for ADP as the angle goes forward. This finding explains not only its unidirectional nature of rotation, but also its physiological function in ATP synthesis; it would readily bind ADP from solution when rotated backward by an Fo motor in the ATP synthase. Furthermore, the mechanical work for the forced rotation was efficiently converted into work for expelling ADP from the catalytic site, supporting the tight coupling between the rotation and catalytic event.
AB - A rotary motor F1, a catalytic part of ATP synthase, makes a 120° step rotation driven by hydrolysis of one ATP, which consists of 80° and 40° substeps initiated by ATP binding and probably by ADP and/or Pi dissociation, respectively. During active rotations, F 1 spontaneously fails in ADP release and pauses after a 80° substep, which is called the ADP-inhibited form. In the present work, we found that, when pushed >+40° with magnetic tweezers, the pausing F1 resumes its active rotation after releasing inhibitory ADP. The rate constant of the mechanical activation exponentially increased with the pushed angle, implying that F1 weakens the affinity of its catalytic site for ADP as the angle goes forward. This finding explains not only its unidirectional nature of rotation, but also its physiological function in ATP synthesis; it would readily bind ADP from solution when rotated backward by an Fo motor in the ATP synthase. Furthermore, the mechanical work for the forced rotation was efficiently converted into work for expelling ADP from the catalytic site, supporting the tight coupling between the rotation and catalytic event.
KW - ADP inhibition
KW - ATP synthase
KW - F1-ATPase
KW - Magnetic tweezers
KW - Single-molecule observation
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UR - http://www.scopus.com/inward/citedby.url?scp=15444367613&partnerID=8YFLogxK
U2 - 10.1073/pnas.0406486102
DO - 10.1073/pnas.0406486102
M3 - Article
C2 - 15758075
AN - SCOPUS:15444367613
VL - 102
SP - 4288
EP - 4293
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 - 12
ER -