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Related Concept Videos

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.
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...
Surface Appendages of Archaea01:23

Surface Appendages of Archaea

Archaeal surface appendages are highly specialized structures essential for environmental adaptation, encompassing roles in adhesion, biofilm formation, and motility. Among these appendages, pili and archaella stand out for their distinct morphologies and functionalities, enabling archaea to thrive in diverse and often extreme environments.Pili: Adhesion and Biofilm FormationPili are filamentous structures assembled from pilin protein subunits, primarily contributing to adhesion and biofilm...
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...
Nucleoid01:24

Nucleoid

The nucleoid represents a structurally and functionally distinct region within prokaryotic cells, where the cell's DNA and associated proteins are housed. Unlike eukaryotic cells, prokaryotes lack a membrane-bound nucleus, and the nucleoid facilitates the organization and accessibility of the genetic material within this constraint. The DNA in most bacteria and archaea exists as a single, circular, double-stranded molecule that is highly compacted through supercoiling and interactions with...
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.

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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

An actin-based cytoskeleton in archaea.

Thijs J G Ettema1, Ann-Christin Lindås, Rolf Bernander

  • 1Department of Molecular Evolution, Evolutionary Biology Center, Uppsala University, Norbyvägen 18C, SE-752 36, Uppsala, Sweden. Thijs.Ettema@ebc.uu.se

Molecular Microbiology
|March 19, 2011
PubMed
Summary
This summary is machine-generated.

Researchers discovered an archaeal cytoskeleton in Pyrobaculum calidifontis, featuring Crenactin, an actin homolog. This finding suggests a crenarchaeal origin for the eukaryotic actin cytoskeleton, impacting theories on eukaryotic cell evolution.

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Visualizing Actin and Microtubule Coupling Dynamics In Vitro by Total Internal Reflection Fluorescence (TIRF) Microscopy
08:44

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

Published on: July 20, 2022

Area of Science:

  • Cell Biology
  • Archaea Research
  • Evolutionary Biology

Background:

  • Eukaryotic and bacterial cell organization relies on cytoskeletal filaments, with actin being crucial for eukaryotic cell shape, force generation, and division.
  • The existence and function of cytoskeletons in Archaea remain less understood compared to other domains of life.

Purpose of the Study:

  • To investigate the presence and nature of a cytoskeleton in the archaeon Pyrobaculum calidifontis.
  • To identify the molecular components of this archaeal cytoskeleton and their potential functions.
  • To explore the evolutionary implications of archaeal cytoskeletal elements for the origin of eukaryotic cells.

Main Methods:

  • In situ immunostaining was employed to visualize cytoskeletal structures within Pyrobaculum calidifontis cells.
  • Genetic analysis identified an archaeal actin homologue, Crenactin, and its associated gene cluster, Arcade.
  • Phylogenetic analysis was conducted to determine the distribution of arcade genes across archaeal lineages.

Main Results:

  • An archaeal cytoskeleton forming helical structures was identified in Pyrobaculum calidifontis.
  • Crenactin, an archaeal actin homologue, was identified as a core component, related to eukaryotic actin.
  • The Arcade gene cluster, including genes for Arcadin proteins, was found in specific archaeal lineages (Thermoproteales, Korarchaeota) correlating with cell morphology.
  • Arcadin proteins showed distinct localizations, with some forming helical structures and Arcadin-2 potentially involved in cell division.

Conclusions:

  • The study reveals a functional cytoskeleton in Archaea, composed of Crenactin and other Arcadin proteins.
  • The findings provide strong evidence for a crenarchaeal origin of the eukaryotic actin cytoskeleton.
  • This discovery has significant implications for understanding the early evolution of eukaryotic cells and the emergence of complex cellular structures.