TY - JOUR
T1 - Direct Optical Microscopic Observation of the Microtubule Polymerization Intermediate Sheet Structure in the Presence of Gas7
AU - Uchida, Takafumi
AU - Akiyama, Hirotada
AU - Sakamoto, Wataru
AU - Koga, Tomoe
AU - Yan, Kangmin
AU - Uchida, Chiyoko
AU - Hirose, Keiko
AU - Itoh, Tomohiko J.
N1 - Funding Information:
T.U. was supported by a Grant-in-Aid for Scientific Research on Priority Areas and a Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science, and Technology of Japan. We thank Mariko Sanada and Akiko Fujita for technical help.
PY - 2009/9/4
Y1 - 2009/9/4
N2 - The process of microtubule elongation is thought to consist of two stages-formation of a tubulin sheet structure and its closure into a tube. However, real-time observation of this process has been difficult. Here, by utilizing phospho-tau binding protein Gas7 (growth-arrest-specific protein 7), we visualized the polymer transformation process by dark-field microscopy. Upon elongation, thin and flexible structures, often similar to a curved hook, appeared at the end of microtubules. Electron microscopic observations supported the idea that these flexible structures are tubulin sheets. They maintained their length until they gradually became thick and rigid beginning in the central portion, resulting in straight microtubules. In the absence of Gas7, the sheet-like structure was rarely observed; moreover, when observed, it was fragile and engaged in typical dynamic instability. With Gas7, no catastrophe was observed. These results suggest that Gas7 enhances microtubule polymerization by stabilizing sheet intermediates and is a useful tool for analyzing microtubule transformation.
AB - The process of microtubule elongation is thought to consist of two stages-formation of a tubulin sheet structure and its closure into a tube. However, real-time observation of this process has been difficult. Here, by utilizing phospho-tau binding protein Gas7 (growth-arrest-specific protein 7), we visualized the polymer transformation process by dark-field microscopy. Upon elongation, thin and flexible structures, often similar to a curved hook, appeared at the end of microtubules. Electron microscopic observations supported the idea that these flexible structures are tubulin sheets. They maintained their length until they gradually became thick and rigid beginning in the central portion, resulting in straight microtubules. In the absence of Gas7, the sheet-like structure was rarely observed; moreover, when observed, it was fragile and engaged in typical dynamic instability. With Gas7, no catastrophe was observed. These results suggest that Gas7 enhances microtubule polymerization by stabilizing sheet intermediates and is a useful tool for analyzing microtubule transformation.
KW - Gas7
KW - MAPs
KW - Pin1
KW - dark-field microscopy
KW - intermediate sheet
KW - microtubule polymerization
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U2 - 10.1016/j.jmb.2009.06.081
DO - 10.1016/j.jmb.2009.06.081
M3 - Article
C2 - 19580814
AN - SCOPUS:68349123588
VL - 391
SP - 849
EP - 857
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
SN - 0022-2836
IS - 5
ER -