title: Is proteomics a reliable tool to probe the oxidative folding of bacterial membrane proteins?
abstract: The oxidative folding of proteins involves disulfide bond formation, which is usually catalyzed by thiol-disulfide oxidoreductases (TDORs). In bacteria, this process takes place in the cytoplasmic membrane and other extracytoplasmic compartments. While it is relatively easy to study oxidative folding of water-soluble proteins on a proteome-wide scale, this has remained a major challenge for membrane proteins due to their high hydrophobicity. Here, we have assessed whether proteomic techniques can be applied to probe the oxidative folding of membrane proteins using the Gram-positive bacterium Bacillus subtilis as a model organism. Specifically, we investigated the membrane proteome of a B. subtilis bdbCD mutant strain, which lacks the primary TDOR pair BdbC and BdbD, by gel-free mass spectrometry. In total, 18 membrane-associated proteins showed differing behavior in the bdbCD mutant and the parental strain. These included the ProA protein involved in osmoprotection. Consistent with the absence of ProA, the bdbCD mutant was found to be sensitive to osmotic shock. We hypothesize that membrane proteomics is a potentially effective approach to profile oxidative folding of bacterial membrane proteins.
authors.affiliation: Department of Medical Microbiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Vivianne J
authors.initials: VJ
authors.lastname: Goosens
authors.forename: Ruben A T
authors.initials: RA
authors.lastname: Mars
authors.forename: Michiel
authors.initials: M
authors.lastname: Akeroyd
authors.forename: Andre
authors.initials: A
authors.lastname: Vente
authors.forename: Annette
authors.initials: A
authors.lastname: Dreisbach
authors.forename: Emma L
authors.initials: EL
authors.lastname: Denham
authors.forename: Thijs R H M
authors.initials: TR
authors.lastname: Kouwen
authors.forename: Tjeerd
authors.initials: T
authors.lastname: van Rij
authors.forename: Maurien
authors.initials: M
authors.lastname: Olsthoorn
authors.forename: Jan Maarten
authors.initials: JM
authors.lastname: van Dijl
mesh_terms: D001412:Bacillus subtilis / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D017510:Protein Folding; D040901:Proteomics / Q000379:methods*
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins