Related Experiment Video

Updated: Sep 29, 2026

Imaging Plasma Membrane Deformations With pTIRFM
12:28

Imaging Plasma Membrane Deformations With pTIRFM

Published on: April 2, 2014

Conversion of PtdIns(4,5)P(2) into PtdIns(5)P by the S.flexneri effector IpgD reorganizes host cell morphology

Kirsten Niebuhr1, Sylvie Giuriato, Thierry Pedron

  • 1Pathogénie Microbienne Moléculaire, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex 15, France.

The EMBO Journal
|October 3, 2002
PubMed

Insights

Shigella flexneri infection triggers its virulence factor IpgD to convert phosphatidylinositol 4,5-bisphosphate into phosphatidylinositol 5-monophosphate. This phosphoinositide switch causes host cell shape changes, membrane blebbing, and actin remodeling.

Area of Science:

  • Cell Biology
  • Microbiology
  • Biochemistry

Background:

  • Phosphoinositides regulate crucial cellular processes, including actin cytoskeleton dynamics.
  • Pathogenic bacteria often manipulate host cell functions to facilitate infection.

Purpose of the Study:

  • To elucidate the molecular mechanism by which Shigella flexneri IpgD affects host cell morphology.
  • To investigate the role of phosphoinositide metabolism in bacterial invasion.

Main Methods:

  • Bacterial infection of epithelial cells with Shigella flexneri.
  • Translocation of the virulence factor IpgD into host cells.
  • Biochemical assays to determine IpgD's enzymatic activity (inositol 4-phosphatase).
  • Analysis of phosphoinositide levels (PtdIns(4,5)P2 and PtdIns(5)P).
  • Cellular imaging to assess morphological changes, membrane tether force, and actin remodeling.

Main Results:

  • The Shigella flexneri virulence factor IpgD acts as an inositol 4-phosphatase.
  • IpgD specifically dephosphorylates phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] to phosphatidylinositol 5-monophosphate [PtdIns(5)P].
  • Accumulation of PtdIns(5)P leads to significant host cell morphological alterations, including decreased membrane tether force, membrane blebbing, and actin filament reorganization.

Conclusions:

  • IpgD-mediated conversion of PtdIns(4,5)P2 to PtdIns(5)P is responsible for host cell shape changes during Shigella flexneri infection.
  • This phosphoinositide modification is a key mechanism employed by the pathogen to induce membrane ruffling at the entry site.
  • The study reveals a novel bacterial strategy for manipulating host cell cytoskeleton and membrane dynamics.

More Related Videos

Genetic Engineering of Dictyostelium discoideum Cells Based on Selection and Growth on Bacteria06:08

Genetic Engineering of Dictyostelium discoideum Cells Based on Selection and Growth on Bacteria

Published on: January 25, 2019

Imaging and Analysis of Tissue Orientation and Growth Dynamics in the Developing Drosophila Epithelia During Pupal Stages08:25

Imaging and Analysis of Tissue Orientation and Growth Dynamics in the Developing Drosophila Epithelia During Pupal Stages

Published on: June 2, 2020

Related Concept Videos

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...
Phosphoinositides and PIPs01:42

Phosphoinositides and PIPs

Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Mechanism of Lamellipodia Formation01:31

Mechanism of Lamellipodia Formation

Cells migrating in response to external stimuli form lamellipodia, which are thin membrane protrusions supported by a mesh of linked, branched, or unbranched actin filaments. These actin filaments interact with myosin motor proteins, creating the dynamic actomyosin complex within the cytoskeleton. Contractility, or the ability to generate contractile stress, is inherent to the actomyosin complex. It helps cells detect the stiffness of the surrounding ECM and exert contractile force for...
Intrinsically Disordered Proteins02:18

Intrinsically Disordered Proteins

Intrinsically disordered proteins are a group of proteins that do not fold into specific three-dimensional structures. Their structural flexibility allows them to complement ordered proteins to perform functions that are inaccessible to rigid structures. They are more common in eukaryotes than prokaryotes and may either be exclusively intrinsically disordered or hybrid proteins, consisting of a mix of ordered and disordered regions. The absence of a rigid structure in these proteins can be...
Pinching-off of Coated Vesicles01:32

Pinching-off of Coated Vesicles

Vesicle budding is orchestrated by distinct cytosolic proteins such as adaptor proteins, coat proteins, and GTPases. To initiate vesicle budding, membrane-bending proteins containing crescent-shaped BAR domains bind to the lipid heads in the bilayer and distort the membrane to form a protein-coated vesicle bud. Adaptors proteins such as AP2 for clathrin-coated vesicles can nucleate on the deformed membrane. Finally, coat proteins such as clathrin or COPI and COPII assemble into a coat forming...
IP3/DAG Signaling Pathway01:11

IP3/DAG Signaling Pathway

Membrane lipids such as phosphatidylinositol (PI) are precursors for several membrane-bound and soluble second messengers. Specific kinases phosphorylate PI and produce phosphorylated inositol phospholipids. One such inositol phospholipids are the  phosphatidylinositol-4,5 bisphosphate [PI(4,5)P2], present in the inner half of the lipid bilayer. Upon ligand binding, GPCR stimulates Gq proteins to turn on phospholipase Cꞵ. Activated phospholipase Cꞵ cleaves PI(4,5)P2 and produces two-second...