Yiying Yang thesis defense

09 December 2021 par Patricia Siguier
Mechanisms of the biogenesis and maintenance of the outer membrane in Gram-negative bacteria.

Wednesday, 15th December 2021

Yiying Yang will present the results of her PhD work on the mechanisms of the biogenesis and maintenance of the outer membrane in Gram-negative bacteria.


Gram-negative bacteria include a number of dreadful animal pathogens that are particularly resistant to antibiotic therapies thanks to the sheltering function of their bacterial envelope. The envelope is composed of an inner and an outer membrane (IM and OM), and the separating periplasm containing the peptidoglycan (PG). The outer leaflet of the OM bilayer largely consists of lipopolysaccharide (LPS) that forms a permeability barrier against toxic molecules, including detergents and small hydrophobic molecules. Nutrients are transported via OM-spanning proteins (OMPs). Other OMPs perform envelope biogenesis functions, including the assembly of OMPs and LPS. OMPs are assembled into the OM by the beta-barrel assembly machinery (BAM), a heteropentamer containing the essential OMP BamA and four lipoproteins BamBCDE. The assembly of LPS requires another essential OMP, LptD, which stably associates with the lipoprotein LptE. Defective assembly of OMPs causes envelope stress and renders Gram-negative bacteria sensitive to antibiotics and detergents. Hence, the BAM complex represents a promising target for the development of new therapies.The mechanistic details of how the BAM complex functions ensuring efficient OM biogenesis are only marginally understood. By using a quantitative mass-spectrometry strategy the hosting lab has recently identified two novel putative interactors of the BAM complex of Escherichia coli, the lipoproteins DolP (formerly YraP) and BilB, both of unknown functions. The aim of this PhD thesiswork was to characterize the roles of DolP and BilB at the BAM complex.

Raffaele Ieva team