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ISSN 1672-9145 Acta Biochim Biophys Sin 2004, 36(9): 637–643 CN 31-1940/Q

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Preliminarily Investigating the Polymorphism of Self-organized Actin Filament in Vitro by Atomic Force Microscope

Jun ZHANG^1,2, Yuan-Liang WANG¹*, Xin-Yong Chen³, Chuang-Long HE¹, Chao CHENG¹, and Yang CAO¹

¹Key Lab of Biomechanics & Tissue Engineering, Chongqing University, Chongqing 400044, China;

²Biology Department, Chongqing University of Medicine Sciences, Congqing 400016, China;

³Laboratory of Biophysics and Surface Analysis, University of Nottingham, Nottingham NG7 2RD, United Kingdom

Abstract With the atomic force microscope (AFM), we preliminarily investigated the large-scale structure of actin filaments formed in low concentration protein solution (5 mg/ml) via self-organization without the presence of any F-actin dynamic interfering factors (such as phalloidin) in vitro. It was found that the G-actin could be polymerized into ordered filamentous structures with different diameter from the slimmest filament of single F-actin to giant filament in tree-like branched aggregates. The observed polymerized actin filaments, to which our most intense attention was attracted, was discretely distributed and showed obvious polymorphism distinctly different from those in the presence of phalloidin or actin binding proteins (fimbrin, gelsolin, etc.) in previous experiments. Latter structures were mainly composed of single F-actin and/or multifilaments clearly consisting of several single F-actin. The experimental results clearly demonstrated that non-interference with the F-actin intrinsic dynamics in self-organizing could lead to the polymorphism of actin filamentous structures, and further analysis implied that the disturbance of normal F-actin dynamics by many factors could prevent the emergence of structural polymorphism, more often than not, give rise to formation of specific structures instead and different interference would bring about various particular structures under certain conditions.

Key words actin; self-organization; filamentous structure; polymorphism; atomic force microscope

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Received: April 6, 2004 Accepted: August 6, 2004

This work was supported by the grants from the National Natural Science Foundation of China [No. 19732030 (Key Program), No. 19732003, No. 19872080], and the Visiting Scholar Foundation of Key Lab in Chongqing University

*Corresponding author: Tel, 86-23-65102508; Fax, 96-23-65316247; E-mail, [email protected]