title: Dissecting Escherichia coli outer membrane biogenesis using differential proteomics.
abstract: The cell envelope of Gram-negative bacteria is a complex multi-layered structure comprising an inner cytoplasmic membrane and an additional asymmetric lipid bilayer, the outer membrane, which functions as a selective permeability barrier and is essential for viability. Lipopolysaccharide, an essential glycolipid located in the outer leaflet of the outer membrane, greatly contributes to the peculiar properties exhibited by the outer membrane. This complex molecule is transported to the cell surface by a molecular machine composed of seven essential proteins LptABCDEFG that form a transenvelope complex and function as a single device. While advances in understanding the mechanisms that govern the biogenesis of the cell envelope have been recently made, only few studies are available on how bacterial cells respond to severe envelope biogenesis defects on a global scale. Here we report the use of differential proteomics based on Multidimensional Protein Identification Technology (MudPIT) to investigate how Escherichia coli cells respond to a block of lipopolysaccharide transport to the outer membrane. We analysed the envelope proteome of a lptC conditional mutant grown under permissive and non permissive conditions and identified 123 proteins whose level is modulated upon LptC depletion. Most such proteins belong to pathways implicated in cell envelope biogenesis, peptidoglycan remodelling, cell division and protein folding. Overall these data contribute to our understanding on how E. coli cells respond to LPS transport defects to restore outer membrane functionality.
authors: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
authors: Alessandra M
authors: AM
authors: Martorana
authors: Istituto di Tecnologie Biomediche (ITB-CNR), Segrate, Milan, Italy.
authors: Sara
authors: S
authors: Motta
authors: Istituto di Tecnologie Biomediche (ITB-CNR), Segrate, Milan, Italy.
authors: Dario
authors: D
authors: Di Silvestre
authors: Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
authors: Federica
authors: F
authors: Falchi
authors: Dipartimento di Bioscienze, Università degli Studi di Milano, Milan, Italy.
authors: Gianni
authors: G
authors: Dehò
authors: Istituto di Tecnologie Biomediche (ITB-CNR), Segrate, Milan, Italy.
authors: Pierluigi
authors: P
authors: Mauri
authors: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
authors: Paola
authors: P
authors: Sperandeo
authors: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, Milan, Italy.
authors: Alessandra
authors: A
authors: Polissi
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001692:Biological Transport; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D021381:Protein Transport; D020543:Proteome; D040901:Proteomics / Q000379:methods; D013312:Stress, Physiological
chemical_list: D001425:Bacterial Outer Membrane Proteins; D029968:Escherichia coli Proteins; D008070:Lipopolysaccharides; C543318:LptC protein, E coli; D008565:Membrane Proteins; D020543:Proteome