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Figure 12.4 Various biological processes
captured by high-speed AFM. The number
attached to each image indicates the frame
number (F#). (a) Myosin V head bending upon
UV-flash photolysis of caged ATP. F#86: before
UV flash; F#87
first UV flash; F#22: after the second UV
flash. Scale bar, 100 nm; imaging rate, 1 s/frame.
(c) Movement of kinesin
gelsolin along a
microtubule. Arrow heads indicate
kinesin
-
gelsolin. Scale bar, 100 nm; imaging
rate, 0.64 s/frame. (d) Actin filaments gliding
over a surface that is densely coated with myosin
V. Scale bar, 200 nm; imaging rate, 1 s/frame.
-
105: after UV flash. Scale bar,
30 nm; imaging rate, 80ms/frame. (b) GroES
binding to GroEL upon UV-flash photolysis of
caged ATP. F#11: before UV flash; F#13: after the
-
observation of GroES binding to GroEL. In this observation, GroEL was densely
coated onto a mica surface in an end-up orientation with GroES
floating in an
ATP-contained solution. We were able to observe GroES binding immediately after
UV
flashes (Figure 12.4b).
In 2003, we developed the
first version of the dynamic PID controller to reduce
the tapping force. Using this controller, we imaged at 0.5 s/frame unidirectional
movement of a chimera kinesin along a microtubule in an ATP-containing
solution [18]. For this kinesin, the C-terminal tail ends were replaced with gelosolin
to avoid strong attachment of its intrinsic tail ends to the mica surface. The observed
kinesin moved unidirectionally along a microtubule while attaching weakly to the
mica surface (Figure 12.4c). Kinesin moving along a microtubule without touching
the mica surface was not observed. This is because tip-sample interaction was still
too strong even when applying the
first version of our dynamic PID controller.
The tip removed kinesin attached only to the microtubules. In the absence of the
