Motility and structural polymorphism of polymer-actin complex gel.
Hyuck Joon Kwon1, Kazuhiro Shikinaka, Akira Kakugo
1Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
Journal of Nanoscience and Nanotechnology
|April 25, 2007
Summary
Researchers created a bio-actuator from muscle proteins. This soft gel machine moves like native F-actin by utilizing ATP hydrolysis and can be shaped for specific applications.
Area of Science:
- Biomaterials Science
- Soft Robotics
- Biophysics
Background:
- Muscle proteins like actin and myosin are fundamental to biological movement.
- Developing artificial actuators that mimic biological systems is a key challenge in soft robotics.
Purpose of the Study:
- To engineer a functional soft gel machine using muscle proteins.
- To investigate the relationship between gel morphology and motility.
- To control the shape and size of the bio-actuator.
Main Methods:
- Chemically cross-linking polymer-actin complexes.
- Utilizing ATP hydrolysis to drive movement on a myosin-coated surface.
- Investigating structural behavior by altering electrostatic interactions between F-actins and polycations.
Main Results:
- The polymer-actin complex gel exhibited movement comparable to native F-actin, powered by ATP hydrolysis.
- Gel velocity and motion patterns were found to be dependent on the gel's morphology.
- Morphology and growth size were controllable by manipulating electrostatic interactions.
Conclusions:
- A bio-actuator capable of directed movement has been successfully reconstructed from muscle proteins.
- The ability to control gel morphology allows for the design of bio-actuators with desired shapes.
- This work opens possibilities for creating custom-shaped bio-actuators for various applications.
Related Concept Videos
01:13Actin Polymerization and Cell Motility
Actin is a family of globular proteins that are highly abundant in eukaryotic cells. It makes up approximately 1-5% of total cell protein concentration. Actin monomers polymerize to form a complex network of polarized filaments, the actin cytoskeleton, that plays a crucial role in many cellular processes, including cell motility, division, endocytosis, and metastasis of cancer cells.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
Actin cytoskeleton dynamics can produce pushing, pulling, and resistance forces that help the cell to migrate.
01:11Formation of Higher-order Actin Filaments
The polymerization of G-actin monomers into filamentous F-actin is a multi-step process. Once the F-actins are formed, they can bundle together in different arrangements to form higher-order networks and regulate cellular functions. Common examples include the formation of lamellipodia and filopodia at the cell's leading edge by actin reorganization in a migrating cell. The microvilli on the brush border epithelial cells are also formed through the F-actin network.
The high-order actin networks...
The high-order actin networks...
01:42Actin Polymerization
Actin polymerization occurs through the head-to-tail association of binding sites on monomeric actin or G-actin to form filamentous or F-actin. The polymerization can be divided into three phases ̶ nucleation, elongation, and steady-state phase.
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
The nucleation phase involves forming a stable nucleus consisting of three actin monomers to form a new actin filament. Actin-binding proteins such as formins and Arp2/3 complex help filament growth post-nucleation. The Formins form straight actin...
01:18Actin Treadmilling
Actin filaments undergo polymerization and depolymerization from either end. The polymerization and depolymerization rates depend on the cytosolic concentration of free G-actins. The polymerization rate is generally higher at the plus or barbed end, while the depolymerization rate is higher at the minus or pointed end. At a steady state, critical concentration describes the concentration of free G-actin monomers at which the polymerization rate at the plus end is equal to that of the...
01:19Actin Filament Depolymerization
Actin filaments (F-actin) are composed of actin subunits. The dissociation of actin monomers can occur from either end of F-actin. The rate of dissociation is faster from the minus-end or the pointed end, where the actin subunits exist with a bound ADP, together known as ADP-actin. The depolymerization of F-actin is aided by proteins, including the actin-depolymerizing factor (ADF) and cofilin family of proteins, gelsolin, and glia maturation factor (GMF).
In F-actin, the ADF/cofilin proteins...
In F-actin, the ADF/cofilin proteins...
01:26Introduction to Actin
Actin is a highly conserved cytoskeletal protein found abundantly in eukaryotic cells. It constitutes 10% weight of the total cellular protein in muscle cells, while in non-muscle cells, it is lower and makes up around 1–5 percent of the total cell protein. Actin found in the unicellular amoebae and complex multicellular animals is around 80% similar, demonstrating their conservation over a billion years of evolution. Actin coding genes are conserved within species and across different species.