Structural characterization of Type III Secretion System related translocator and effector from Pseudomonas aeruginosa
IR@IICB: CSIR-Indian Institute of Chemical Biology, Kolkata
View Archive Info| Field | Value | |
| Title |
Structural characterization of Type III Secretion System
related translocator and effector from Pseudomonas aeruginosa
|
|
| Creator |
Dey, Supratim
|
|
| Subject |
Structural Biology & Bioinformatics
|
|
| Description |
Pseudomonas aeruginosa, a Gram-negative pathogen utilizes a specialized set of Type III
Secretion System (T3SS) translocator and effector proteins to establish virulence in the host
cell. An understanding of these pathogenic factors that play a key role in the establishment
and maintenance of bacterial pathogenicity are thus, of immense importance, and are likely
the interest of study of several research groups.
The T3SS encoding “translocator operon” of P. aeruginosa consists of a major translocator
protein PopB, minor translocator protein PopD and their cognate chaperone PcrH. We
present a comprehensive study of PopB structure, its interaction with PcrH and their
associated pH-based structural and functional changes. The pH-dependent studies indicate
that PcrH not only provides structural support to the ordered molten globule PopB in
complex but also undergoes conformational change to assist PopB to pass through the needle
complex of T3SS and form pores in the host cell membrane. In addition, we report an abinitio
model of PopB docked to PcrH, which together with PCR-based deletion mutations and
SPR studies determine the terminal domains of PopB to be involved in hydrophobic
interaction with PcrH as well as maintain the oligomerisation of translocator complex.
Amongst all effector toxin proteins of T3SS present in P. aeruginosa, both ExoT and ExoS
are considered to be actual virulence determinants. Here, we report the first X-ray crystal
structure of the amino-terminal fragment of effector toxin ExoT, in complex with full-length
homodimeric chaperone SpcS at 2.1Å resolution. The full-length dimeric chaperone SpcS has
the conserved α-β-β-β-α-β-β-α fold of class I chaperones, the characteristic hydrophobic
patches for binding effector proteins and a conserved polar cavity at the dimeric interface.
The stable crystallized amino-terminal fragment of ExoT consists of a chaperone binding
domain and a membrane localization domain that wraps around the dimeric chaperone. Sitedirected
mutagenesis experiments and molecular dynamics study complement each other in
revealing Asn65, Phe67 and Trp88 as critical dimeric interfacial residues that can strongly
influence the effector-chaperone interactions.
This structural and functional T3SS study can thus serve to be promising drug candidates to
combat host cell infections.
|
|
| Date |
2014-03-03
|
|
| Type |
Thesis
NonPeerReviewed |
|
| Format |
application/pdf
|
|
| Identifier |
http://www.eprints.iicb.res.in/2127/1/SupratimThesis_Final.pdf
Dey, Supratim (2014) Structural characterization of Type III Secretion System related translocator and effector from Pseudomonas aeruginosa. PhD thesis, CU. |
|
| Relation |
http://www.eprints.iicb.res.in/2127/
|
|