| Project/Area Number |
17590390
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Osaka University |
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Principal Investigator |
KUBORI Tomoko Osaka University, Research Institute for Microbial Diseases, SAAssistant Professor (20397657)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAI Hiroki Osaka University, Research Institute for Microbial Diseases, SAAssociate Professor (80222173)
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| Project Period (FY) |
2005 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2006: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 2005: ¥2,600,000 (Direct Cost: ¥2,600,000)
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| Keywords | Pathogenic bacteria / Legionella / type IV secretion system / 電子顕微鏡 |
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| Research Abstract |
Legionella pneumophila utilizes the Dot/Icm typeIV secretion system (T4SS) to translocate 'effector proteins' or virlence factors to host cells. The Dot/Icm T4SS is a supramolecular structure which bridges between bacterial inner and outer membranes and more than 20 Dot/Icm proteins are involved in the function and assembly of the system. However the component proteins and the molecular architecture had not been elucidated. It is anticipated that the molecular structure and the working mechanism do not closely resemble to the type III secretion system (T3SS) which has been well studied. To understand the molecular mechanisms how Legionella subverts and utilizes the host cellular functions for successful infection, we have been examining the molecular structure of the Dot/Icm T4SS.
Isolating the bacterial membrane fractions and biochemically analyzing them lead us to find that the core complex of the Dot/Icm T4SS is composed of the five proteins, DotH, DotC, DotD, DotF and DotG. For these proteins we analyzed the bacterial surface localization, mutual dependency for the complex assembly and protein-protein interactions. The results showed that DotH, DotC and DotD form the sub-complex located in the outer membrane and that two inner-membrane spanning proteins DotF and DotG associate with the DotH/DotC/DoD complex to built up the entire core complex bridging between the inner and outer membranes.
Irrespective of being a core component, DotF protein was found to be dispensable for the secretion function, although it is known to interact with many Dot/Icm T4SS substrate proteins. The unexpected result suggests that DotF is vital for efficient Dot/Icm core complex assembly
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