Related Experiment Video

Updated: Aug 11, 2026

Aip1p Dynamics Are Altered by the R256H Mutation in Actin
08:57

Aip1p Dynamics Are Altered by the R256H Mutation in Actin

Published on: July 30, 2014

Actin's prokaryotic homologs

Edward H Egelman1

  • 1Department of Biochemistry and Molecular Genetics, University of Virginia Health Sciences Center, Box 800733, Charlottesville 22908-0733, USA. egelman@virginia.edu

Current Opinion in Structural Biology
|May 3, 2003
PubMed

Insights

Prokaryotic homologs of actin, MreB and ParM, polymerize into filaments. Unlike highly conserved eukaryotic actin, bacterial actin homologs show less sequence similarity, suggesting evolutionary flexibility.

Area of Science:

  • Biochemistry
  • Molecular Biology
  • Microbiology

Background:

  • Actin is a highly conserved eukaryotic protein essential for cellular functions.
  • Prokaryotic homologs, MreB and ParM, have been recently identified.
  • MreB and ParM polymerize into filaments, influencing bacterial cell shape and plasmid segregation.

Purpose of the Study:

  • To investigate the evolutionary conservation and sequence similarity of eukaryotic actin and its prokaryotic homologs.
  • To understand the functional implications of sequence divergence between bacterial and eukaryotic actin-like proteins.

Main Methods:

  • Sequence analysis of actin and its prokaryotic homologs (MreB, ParM).
  • Comparative analysis of protein sequence identity and conservation patterns.

Main Results:

  • Eukaryotic actins exhibit remarkable sequence conservation across species.
  • Prokaryotic actin homologs (MreB and ParM) share only approximately 11% sequence identity with each other and with actin.
  • Bacterial homologs show greater sequence divergence compared to eukaryotic actins.

Conclusions:

  • The functional properties of eukaryotic F-actin may drive its high conservation.
  • Bacterial actin homologs (MreB and ParM) have experienced fewer evolutionary constraints, leading to greater sequence diversity.
  • Understanding these differences provides insights into the evolution of cytoskeletal proteins.

More Related Videos

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy08:44

Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy

Published on: July 20, 2022

Reconstitution of Actin-Based Motility with Commercially Available Proteins08:40

Reconstitution of Actin-Based Motility with Commercially Available Proteins

Published on: October 28, 2022

Related Concept Videos

Cytoskeletal Accessory Proteins01:13

Cytoskeletal 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...
Cytoskeletal Proteins in Bacteria01:29

Cytoskeletal Proteins in Bacteria

Bacterial cells were initially considered simple, randomly organized structures lacking a cytoskeleton. However, the discovery of cytoskeleton homologs in bacteria led to the change of this opinion. Bacterial cytoskeletal filaments regulate the cell shape, cell polarity, cell division, and partitioning of plasmids during cell division. It was later discovered that bacterial cytoskeletal proteins, mainly actin and tubulin homologs, are diverse compared to their eukaryotic counterparts. On the...
Introduction to Actin01:26

Introduction 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.
Generation of Straight or Branched Actin Filaments01:14

Generation 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...
Actin Polymerization and Cell Motility01:13

Actin 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.
Bacterial Phylum Actinobacteria01:30

Bacterial Phylum Actinobacteria

Coryneform bacteria are gram-positive, aerobic, nonmotile rods that exhibit irregular, club-shaped, or V-shaped arrangements. Their V-shape results from snapping division, where the inner cell wall layer forms the cross-wall, while the outer layer remains intact until it ruptures on one side, causing the daughter cells to bend away.The primary genera are Corynebacterium and Arthrobacter. Corynebacterium includes diverse species, ranging from saprophytes to pathogens like Corynebacterium...