Abstract
Motor proteins are essential in life processes because they convert the free energy of ATP hydrolysis to mechanical work. However, the fundamental question on how they work when different amounts of free energy are released after ATP hydrolysis remains unanswered. To answer this question, it is essential to clarify how the stepping motion of a motor protein reflects the concentrations of ATP, ADP, and Pi in its individual actions at a single molecule level. The F1 portion of ATP synthase, also called F 1-ATPase, is a rotary molecular motor in which the central γ-subunit rotates against the α3b3 cylinder. The motor exhibits clear step motion at low ATP concentrations. The rotary action of this motor is processive and generates a high torque. These features are ideal for exploring the relationship between free energy input and mechanical work output, but there is a serious problem in that this motor is severely inhibited by ADP. In this study, we overcame this problem of ADP inhibition by introducing several mutations while retaining high enzymatic activity. Using a probe of attached beads, stepping rotation against viscous load was examined at a wide range of free energy values by changing the ADP concentration. The results showed that the apparent work of each individual step motion was not affected by the free energy of ATP hydrolysis, but the frequency of each individual step motion depended on the free energy. This is the first study that examined the stepping motion of a molecular motor at a single molecule level with simultaneous systematic control of ΔGATP. The results imply that microscopically defined work at a single molecule level cannot be directly compared with macroscopically defined free energy input.
| Original language | English |
|---|---|
| Pages (from-to) | 1806-1812 |
| Number of pages | 7 |
| Journal | Biophysical Journal |
| Volume | 92 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 2007 Mar |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biophysics
Cite this
Single molecule energetics of F1-ATPase motor. / Muneyuki, Eiro; Watanabe-Nakayama, Takahiro; Suzuki, Tetsuya; Yoshida, Masasuke; Nishizaka, Takayuki; Noji, Hiroyuki.
In: Biophysical Journal, Vol. 92, No. 5, 03.2007, p. 1806-1812.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Single molecule energetics of F1-ATPase motor
AU - Muneyuki, Eiro
AU - Watanabe-Nakayama, Takahiro
AU - Suzuki, Tetsuya
AU - Yoshida, Masasuke
AU - Nishizaka, Takayuki
AU - Noji, Hiroyuki
PY - 2007/3
Y1 - 2007/3
N2 - Motor proteins are essential in life processes because they convert the free energy of ATP hydrolysis to mechanical work. However, the fundamental question on how they work when different amounts of free energy are released after ATP hydrolysis remains unanswered. To answer this question, it is essential to clarify how the stepping motion of a motor protein reflects the concentrations of ATP, ADP, and Pi in its individual actions at a single molecule level. The F1 portion of ATP synthase, also called F 1-ATPase, is a rotary molecular motor in which the central γ-subunit rotates against the α3b3 cylinder. The motor exhibits clear step motion at low ATP concentrations. The rotary action of this motor is processive and generates a high torque. These features are ideal for exploring the relationship between free energy input and mechanical work output, but there is a serious problem in that this motor is severely inhibited by ADP. In this study, we overcame this problem of ADP inhibition by introducing several mutations while retaining high enzymatic activity. Using a probe of attached beads, stepping rotation against viscous load was examined at a wide range of free energy values by changing the ADP concentration. The results showed that the apparent work of each individual step motion was not affected by the free energy of ATP hydrolysis, but the frequency of each individual step motion depended on the free energy. This is the first study that examined the stepping motion of a molecular motor at a single molecule level with simultaneous systematic control of ΔGATP. The results imply that microscopically defined work at a single molecule level cannot be directly compared with macroscopically defined free energy input.
AB - Motor proteins are essential in life processes because they convert the free energy of ATP hydrolysis to mechanical work. However, the fundamental question on how they work when different amounts of free energy are released after ATP hydrolysis remains unanswered. To answer this question, it is essential to clarify how the stepping motion of a motor protein reflects the concentrations of ATP, ADP, and Pi in its individual actions at a single molecule level. The F1 portion of ATP synthase, also called F 1-ATPase, is a rotary molecular motor in which the central γ-subunit rotates against the α3b3 cylinder. The motor exhibits clear step motion at low ATP concentrations. The rotary action of this motor is processive and generates a high torque. These features are ideal for exploring the relationship between free energy input and mechanical work output, but there is a serious problem in that this motor is severely inhibited by ADP. In this study, we overcame this problem of ADP inhibition by introducing several mutations while retaining high enzymatic activity. Using a probe of attached beads, stepping rotation against viscous load was examined at a wide range of free energy values by changing the ADP concentration. The results showed that the apparent work of each individual step motion was not affected by the free energy of ATP hydrolysis, but the frequency of each individual step motion depended on the free energy. This is the first study that examined the stepping motion of a molecular motor at a single molecule level with simultaneous systematic control of ΔGATP. The results imply that microscopically defined work at a single molecule level cannot be directly compared with macroscopically defined free energy input.
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UR - http://www.scopus.com/inward/citedby.url?scp=33847779633&partnerID=8YFLogxK
U2 - 10.1529/biophysj.106.097170
DO - 10.1529/biophysj.106.097170
M3 - Article
C2 - 17158579
AN - SCOPUS:33847779633
VL - 92
SP - 1806
EP - 1812
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 5
ER -