Related Experiment Video

Updated: Jul 31, 2026

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking
11:33

Monitoring the Assembly of a Secreted Bacterial Virulence Factor Using Site-specific Crosslinking

Published on: December 17, 2013

The bacterial virulence factors VopL and VopF nucleate actin from the pointed end

Thomas A Burke1, Alyssa J Harker1, Roberto Dominguez2

  • 1Department of Molecular Genetics and Cell Biology, The University of Chicago, Chicago, IL 60637.

The Journal of Cell Biology
|April 2, 2017
PubMed

Insights

VopL/F proteins from infectious Vibrio species primarily act as actin nucleation factors. They briefly associate with the pointed end of actin filaments, influencing host cell actin assembly.

Area of Science:

  • Cell Biology
  • Microbiology
  • Biochemistry

Background:

  • Vibrio species utilize VopL/F proteins, which possess WH2 domains, to manipulate host cell actin assembly.
  • The precise mechanism of VopL/F-mediated actin filament assembly, specifically their association with filament ends, remains debated.

Purpose of the Study:

  • To elucidate the actin filament assembly mechanism of VopL/F proteins.
  • To determine whether VopL/F associate with the barbed or pointed ends of actin filaments.

Main Methods:

  • Utilized multicolor total internal reflection fluorescence microscopy.
  • Observed actin assembly dynamics with fluorescently labeled VopL/F proteins in real-time.

Main Results:

  • VopL/F exclusively nucleate actin filament assembly from monomers, with transient association at the pointed end.
  • VopL/F do not bind to the ends of pre-existing filaments.
  • In the presence of profilin, VopL/F predominantly nucleate from the pointed end, with a minor fraction transiently inhibiting barbed-end elongation.

Conclusions:

  • VopL/F function primarily as actin nucleation factors.
  • VopL/F exhibit transient association with the pointed end of actin filaments during assembly.

More Related Videos

From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins09:55

From Constructs to Crystals – Towards Structure Determination of β-barrel Outer Membrane Proteins

Published on: July 4, 2016

In Vitro Polymerization of F-actin on Early Endosomes12:15

In Vitro Polymerization of F-actin on Early Endosomes

Published on: August 28, 2017

Related Concept Videos

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...
Intracellular Movement of Viruses and Bacteria01:10

Intracellular Movement of Viruses and Bacteria

Intracellular bacteria and viruses often comprise a group of highly infectious pathogens that can cause several diseases. Bacterial pathogens include those belonging to the genus Rickettsia responsible for conditions such as rocky mountain spotted fever and the Mediterranean spotted fever; Chlamydia, a genus responsible for a sexually transmitted disease; Coxiella burnetii, an agent responsible for Q fever. Viral pathogens include vaccinia—a poxvirus, and herpes simplex virus—a virus that...
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...
Mechanism of Filopodia Formation01:39

Mechanism of Filopodia Formation

Filopodia are thin, actin-rich cellular protrusions that play an important role in many fundamental cellular functions. They vary in their occurrence, length, and positioning in different cell types, suggesting their diverse roles.
Their main function is to guide migrating cells during normal tissue morphogenesis or cancer metastasis by recognizing and making initial contacts with the extracellular matrix. However, they can also act as stationary cell anchors or help to establish communication...
Fimbriae, Pili, and Axial Filaments01:28

Fimbriae, Pili, and Axial Filaments

Fimbriae and pili are specialized bacterial surface structures that play pivotal roles in adhesion, genetic exchange, and motility. Composed primarily of pilin protein, these hairlike appendages are crucial for bacterial survival and pathogenicity in various environments.Fimbriae: Adhesion and PathogenicityFimbriae are fine, filamentous structures measuring 2–10 nanometers in diameter and are densely distributed on the bacterial cell surface. They facilitate bacterial adhesion to abiotic...
Regulation of Bacterial Virulence01:28

Regulation of Bacterial Virulence

Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...