Structural characterization of type three secretion system related translocator and regulator proteins from Pseudomonas aeruginosa and Yersinia enterocolitica
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
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| Title |
Structural characterization of type three secretion system
related translocator and regulator proteins from Pseudomonas aeruginosa and Yersinia enterocolitica
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| Creator |
Basu, Abhishek
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| Subject |
Structural Biology & Bioinformatics
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| Description |
Gram negative bacteria Yersinia enterocolitica and Pseudomonas aeruginosa employ a TTSS to inject toxins into the host cell cytoplasm. For the translocation of toxic effectors an injectisome is formed with a translocation apparatus at its tip. This translocon comprises of translocator proteins, controlled by their cognate chaperones and regulators. SycB is a class II chaperone of Ysa-Ysp TTSS of Y. enterocolitica biovar 1B. SycB interacts
with annotated transloctor YspC. YspC is a unique translocator both structurally and evolutionarily. Unlike any other minor hydrophobic translocator, it is highly stable and has a rigid tertiary structure. The model of SycB depicts a concave core with 3 TPR regions and a
flexible N-terminal helix. The N-terminal helix of SycB is essential for its dimerization.However, the dimeric physiological state of SycB dissociates upon interaction with YspC and a 1:1 heterodimeric YspC-SycB complex is formed. SycB attains a molten globule structure with reduction in pH to 5.0, thereby, releasing YspC, which could be a potential signal for activation of TTSS. The first two TPR regions of SycB contain the YspC interaction site. Therefore, the first structural characterization of SycB, YspC, and the structural aspects of YspC-SycB interaction is presented. PcrV is a hydrophilic translocator of P. aeruginosa, regulated by PcrG. The dumbbell shaped model of PcrV depicts two terminal globular domains, and two long helices (7&12) forming the grip of the dumbbell. The PcrG interaction site is localized within helix-7 and helix- 12 of PcrV, with helix-12 being the key mediator of the interaction. The N-terminal globular
domain maintains the physiological state of PcrV. The first intramolecular coiled-coil region of PcrG is responsible for its interaction with PcrV, although the 12 N-terminal residues play an indirect role in the interaction. Also, PcrG could restore the monomeric state of PcrV and
provides structural stability to it. The maintenance of proper state of PcrV prior to translocation is a pre-requisite for formation of functional translocon. Finally, we could propose a model for PcrG-PcrV interaction, where we could show that PcrG sits in a groove formed by helix-7 and helix-12 in between the two globular domains.
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| Date |
2014
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| Type |
Thesis
NonPeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://www.eprints.iicb.res.in/2000/1/ABHISHEK_BASU%2C_Ph.D._Thesis.pdf
Basu, Abhishek (2014) Structural characterization of type three secretion system related translocator and regulator proteins from Pseudomonas aeruginosa and Yersinia enterocolitica. PhD thesis, Calcutta University. |
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| Relation |
http://www.eprints.iicb.res.in/2000/
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