analyse_article_MIETTE

Presentation

scientific articleanalysis

Mathilde MIETTE

Start

context

Porphyromonas gingivalis is a Gram-negative bacterium

associated with periodontal diseases, chronic infections causing inflammation and the destruction of tooth-supportin tissues.

This bacterium is particularly virulent due to a set of toxic proteins it secretes. The Type IX secretion system (T9SS), specific to Bacteroidetes, is essential for the virulence of P. gingivalis

Figure 1. Porphyromonas gingivalis influences the development of multiple chronic inflammatory conditions

objectives

study

• The structure of the C-terminal OmpA_C domain of the PorE protein, a key component of the T9SS

• The interaction between PorE and peptidoglycan to understand its potential role in anchoring the T9SS to the bacterial cell wall

experimental results

X-ray crystallography

Sequence alignment

Structure determination of type porE OmpA_C domain

Comparison with other OmpA_C proteins

Overall structure and peptidoglycan binding site

electronic density cards

Determination of the PorE OmpA_C domain structure

used methods

crystallization of two soluble domains: CRD and OmpA_C-like

X-ray diffraction

OmpA_C-like domain structure

a β leaflet with three strands

five α-helixes

Figure 1 : Schematic representation of PorE 's putative role in anchoring T9SS to the bacterial cell wall

overwallstructureanDpeptidoglycan binding site

• PorE interacts with peptidoglyconan via specific residues

• Fragment PG : Interacts mainly with the protein via the DAP residue

• Hydrogen bonds ( Asp 576, Asn 584 et Arg 591)

figure 2 : Global structure of the PorE-like OmpA_C domain in complex with a peptidoglycan fragment

discussion

Role of the OmpA_C-like domain The C-terminal OmpA_C-like domain of PorE: - Binds strongly to peptidoglycan (PG) - Acts as a bridge linking the outer membrane to the PG network -Plays a crucial role in T9SS stabilization

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