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Structure-function analysis of invasion plasmid antigen C (IpaC) from Shigella flexneri
Lisa A Kueltzo1, John Osiecki, Jeff Barker
1Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66045, USA.
The Journal of Biological Chemistry
|November 13, 2002
Summary
Structural studies of Invasion plasmid antigen C (IpaC) reveal its role in Shigella flexneri pathogenesis. Understanding IpaC
Area of Science:
- Microbiology
- Structural Biology
- Biochemistry
Background:
- Shigella flexneri causes severe gastroenteritis, particularly in children.
- Invasion plasmid antigen C (IpaC) is crucial for bacterial invasion of host cells.
- Detailed structural information on IpaC is lacking, hindering understanding of its mechanism.
Purpose of the Study:
- To elucidate the structure and function of IpaC and its mutants.
- To investigate IpaC's interaction with host cell components.
- To explore the structure-function relationships of IpaC.
Main Methods:
- Circular dichroism and derivative absorbance spectroscopy to analyze protein structure.
- 8-anilino-1-napthalene sulfonic acid (ANS) binding to probe hydrophobic surfaces.
- Liposome interaction assays and linker-scanning mutagenesis.
- Actin nucleation assays.
Main Results:
- Secondary and tertiary structures of IpaC and mutants were characterized.
- Hydrophobic surface exposure and liposome interactions were assessed.
- Domain III (residues 261-363) showed sequence-dependent helical activity.
- IpaC and some mutants demonstrated actin nucleation properties.
Conclusions:
- Structural insights into IpaC provide a basis for understanding its role in host cell invasion.
- Domain III is critical for IpaC function, potentially involving helical structures.
- IpaC's actin nucleation capability contributes to Shigella pathogenesis.