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Processivity of kinesin motility is enhanced on increasing temperature

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ABSTRACT

Kinesin is a motor protein that processively moves step by step along a microtubule. To investigate the effects of temperature on run length, i.e., processivity of kinesin motility, we performed a single-molecular bead assay at temperature range of 20–40°C. An increase in the walking velocity of kinesin corresponded to the Arrhenius activation enthalpy of 48 kJ/mol, being consistent with the previous reports. Here, we found that the run length increased, that is, the kinesin processivity enhanced with increasing temperature. Then, we estimated the probability of detachment of kinesin from a microtubule per one 8-nm stepping event, and found that it diminishes from 0.014 to 0.006/step with increasing temperature from 20 to 40°C. And we noticed that prolonged incubation at 30, 35 and 40°C significantly slowed down the walking velocity, but further increased the run length and duration. Those results are interpreted according to the effect of temperature on the rate constants of some key kinetic steps in the ATPase cycle.

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Temperature dependence of the probability of detachment per each 8 nm step. The probability of detachment was determined to be 0.0143, 0.0121, 0.0086 (0.0085), 0.0075 (0.0053) and 0.0062 (0.0048) at 20, 25, 30, 35 and 40°C, respectively (the values in the parentheses, the data for 6–11 min). Symbols are the same as in Figs. 2–5. For more details, see the text.
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f6-2_13: Temperature dependence of the probability of detachment per each 8 nm step. The probability of detachment was determined to be 0.0143, 0.0121, 0.0086 (0.0085), 0.0075 (0.0053) and 0.0062 (0.0048) at 20, 25, 30, 35 and 40°C, respectively (the values in the parentheses, the data for 6–11 min). Symbols are the same as in Figs. 2–5. For more details, see the text.

Mentions: Based on the above data, we estimated the probability, p, of detachment of kinesin from a microtubule during one cycle of stepping. Now, we assume that the number of cycles (steps) in each processive movement, n, is determined by n = (run length)/(step size). Because the probability that a kinesin molecule detaches after the n-th step is equal to (1−p)n−1p, the average number of steps, <n>, is expressed as <n>=∑n=1∞n(1−p)n–1p=1/p. Thus, the value of p can be determined from the inverse of <n>, that is, the value of p is proportional to the inverse of the average run length. The results of this analysis show that the probability of detachment during one stepping cycle is around 0.01 and decreases with an increase in temperature, meaning that the processivity is enhanced at elevated temperatures (Fig. 6).


Processivity of kinesin motility is enhanced on increasing temperature
Temperature dependence of the probability of detachment per each 8 nm step. The probability of detachment was determined to be 0.0143, 0.0121, 0.0086 (0.0085), 0.0075 (0.0053) and 0.0062 (0.0048) at 20, 25, 30, 35 and 40°C, respectively (the values in the parentheses, the data for 6–11 min). Symbols are the same as in Figs. 2–5. For more details, see the text.
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Related In: Results  -  Collection

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f6-2_13: Temperature dependence of the probability of detachment per each 8 nm step. The probability of detachment was determined to be 0.0143, 0.0121, 0.0086 (0.0085), 0.0075 (0.0053) and 0.0062 (0.0048) at 20, 25, 30, 35 and 40°C, respectively (the values in the parentheses, the data for 6–11 min). Symbols are the same as in Figs. 2–5. For more details, see the text.
Mentions: Based on the above data, we estimated the probability, p, of detachment of kinesin from a microtubule during one cycle of stepping. Now, we assume that the number of cycles (steps) in each processive movement, n, is determined by n = (run length)/(step size). Because the probability that a kinesin molecule detaches after the n-th step is equal to (1−p)n−1p, the average number of steps, <n>, is expressed as <n>=∑n=1∞n(1−p)n–1p=1/p. Thus, the value of p can be determined from the inverse of <n>, that is, the value of p is proportional to the inverse of the average run length. The results of this analysis show that the probability of detachment during one stepping cycle is around 0.01 and decreases with an increase in temperature, meaning that the processivity is enhanced at elevated temperatures (Fig. 6).

View Article: PubMed Central - PubMed

ABSTRACT

Kinesin is a motor protein that processively moves step by step along a microtubule. To investigate the effects of temperature on run length, i.e., processivity of kinesin motility, we performed a single-molecular bead assay at temperature range of 20&ndash;40&deg;C. An increase in the walking velocity of kinesin corresponded to the Arrhenius activation enthalpy of 48 kJ/mol, being consistent with the previous reports. Here, we found that the run length increased, that is, the kinesin processivity enhanced with increasing temperature. Then, we estimated the probability of detachment of kinesin from a microtubule per one 8-nm stepping event, and found that it diminishes from 0.014 to 0.006/step with increasing temperature from 20 to 40&deg;C. And we noticed that prolonged incubation at 30, 35 and 40&deg;C significantly slowed down the walking velocity, but further increased the run length and duration. Those results are interpreted according to the effect of temperature on the rate constants of some key kinetic steps in the ATPase cycle.

No MeSH data available.


Related in: MedlinePlus