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Interactions between flagellar and type III secretion proteins in Chlamydia pneumoniae
Chris B Stone1, David C Bulir, Jodi D Gilchrist
1M,G, DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada.
BMC Microbiology
|January 26, 2010
Summary
Chlamydia pneumoniae flagellar proteins FliI, FlhA, and FliF interact with each other and with type III secretion system components, suggesting a role in bacterial survival.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Flagellar secretion systems are crucial for bacterial motility and environmental navigation.
- Chlamydia pneumoniae, an obligate intracellular pathogen, possesses flagellar protein orthologs with unknown functions.
Purpose of the Study:
- To investigate the function and interactions of flagellar proteins FliI, FlhA, and FliF in Chlamydia pneumoniae.
- To determine if these proteins interact with each other or with components of the type III secretion system.
Main Methods:
- Cloning and expression of full-length FliI and fragments of FlhA and FliF in E. coli.
- Biochemical assays to determine ATPase activity of FliI.
- Bacterial-2-hybrid and GST pull-down assays to analyze protein-protein interactions.
Main Results:
- GST-tagged FliI exhibited ATPase activity.
- The N-terminal domain of FliI interacted with the cytoplasmic domain of FlhA.
- FlhA's cytoplasmic domain interacted with FliF's C-terminus.
- FliI interacted with CdsL and CopN; FlhA interacted with CdsL and Cpn0322.
Conclusions:
- The identified interactions suggest in vivo complex formation of these flagellar proteins in C. pneumoniae.
- Conservation and interaction with type III secretion system components imply a role in bacterial replication and intracellular survival.
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