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A Proposed Chaperone of the Bacterial Type VI Secretion System Functions To Constrain a Self-Identity Protein
Martha A Zepeda-Rivera1, Christina C Saak1, Karine A Gibbs2
1Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA.
Journal of Bacteriology
|March 21, 2018
Summary
The bacterium Proteus mirabilis uses the IdsC protein to regulate the secretion of its self-identity protein IdsD. IdsC maintains IdsD levels and mediates its secretion via the type VI secretion system.
Area of Science:
- Microbiology
- Bacterial communication
- Protein secretion
Background:
- Proteus mirabilis communicates identity via the type VI secretion (T6S) system, secreting the self-identity protein IdsD.
- IdsD secretion is critical for self-versus-nonself recognition in bacterial populations.
Purpose of the Study:
- To investigate the regulation of T6S substrates, specifically IdsD, before secretion.
- To elucidate the mechanism by which the IdsC protein influences IdsD secretion and localization.
Main Methods:
- Observation of IdsD localization in subcellular clusters.
- Analysis of IdsD secretion and localization following amino acid disruptions in IdsC.
- Characterization of IdsC as a DUF4123 family protein.
Main Results:
- IdsD forms clusters independently of T6S machinery.
- The IdsC protein is essential for maintaining IdsD clusters and protein levels.
- Disruptions in IdsC impair IdsD secretion but not its localization into clusters.
Conclusions:
- IdsC functions in dual roles: maintaining IdsD protein levels and mediating its secretion.
- IdsC acts as a chaperone, coupling IdsD sequestration with localization for regulated secretion.
- This mechanism restricts identity communication in bacterial populations.
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