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Investigating the Function of Coronin A in the Early Starvation Response of Dictyostelium discoideum by Aggregation Assays
Published on: June 18, 2016
F-actin binding is essential for coronin 1B function in vivo
Liang Cai1, Alexander M Makhov, James E Bear
1Lineberger Comprehensive Cancer Center, Department of Cell & Developmental Biology, University of North Carolina at Chapel Hill, North Carolina 27599-7295, USA.
Journal of Cell Science
|April 26, 2007
Summary
Coronin 1B binds F-actin via a key arginine residue (R30), crucial for cell migration. This interaction protects actin filaments from depolymerization, impacting cell motility and lamellipodial dynamics.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Coronins are F-actin binding proteins involved in cell migration, phagocytosis, and chemotaxis.
- Coronin 1B regulates actin dynamics at the leading edge of fibroblasts.
- Understanding coronin-F-actin interactions is key to elucidating coronin function.
Purpose of the Study:
- To identify the molecular mechanism of coronin 1B binding to F-actin.
- To investigate the role of F-actin binding in coronin 1B function in cell motility.
Main Methods:
- Actin co-sedimentation assays to determine binding affinity.
- Site-directed mutagenesis to identify critical residues for F-actin binding.
- Analysis of coronin localization and cell motility in wild-type and mutant cells.
Main Results:
- A conserved arginine at position 30 (R30) is essential for coronin 1B binding to F-actin.
- Coronin 1B exhibits high affinity for ATP/ADP-P(i)-F-actin and lower affinity for ADP-F-actin.
- Coronin 1B protects actin filaments from cofilin-induced depolymerization.
- An R30D mutant, unable to bind F-actin, shows inefficient leading-edge localization and impaired cell motility.
Conclusions:
- F-actin binding, mediated by R30, is critical for coronin 1B's role in cell migration.
- Coronin 1B's protective effect on actin filaments is independent of enhanced cofilin binding.
- F-actin binding is essential for coronin 1B's regulation of lamellipodial dynamics and whole-cell motility.
Related Concept Videos
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...
01:11Formation 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...
01:14Generation of Straight or Branched Actin Filaments
The straight or branched structure formation of actin filaments is controlled by nucleating proteins such as the formins and Arp2/3 complex. Formin-mediated assembly results in straight filaments, whereas Arp2/3 protein complex-mediated assembly results in branched actin filaments.
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
Arp2/3 Complex
Arp2/3 complex is a seven-subunit complex consisting of two proteins similar to actin- Arp2 and Arp3, and five other subunits that help keep Arp2 and Arp3 inactive. When required, the complex is...
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.
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.
01:13Cytoskeletal Accessory Proteins
The cytoskeleton is an essential cell component that plays several structural and functional roles. However, the filaments that make up the cytoskeleton cannot function independently and depend on the accessory or ancillary proteins to effectively carry out their function. Accessory proteins associate with cytoskeletal filaments and their monomers, aiding filament formation and function. They also help in the cross-communication among cytoskeletal filaments. Cytoskeletal accessory proteins are...