title: Systematic analysis of native membrane protein complexes in Escherichia coli.
abstract: The cell envelope of Escherichia coli is an essential structure that modulates exchanges between the cell and the extra-cellular milieu. Previous proteomic analyses have suggested that it contains a significant number of proteins with no annotated function. To gain insight into these proteins and the general organization of the cell envelope proteome, we have carried out a systematic analysis of native membrane protein complexes. We have identified 30 membrane protein complexes (6 of which are novel) and present reference maps that can be used for cell envelope profiling. In one instance, we identified a protein with no annotated function (YfgM) in a complex with a well-characterized periplasmic chaperone (PpiD). Using the guilt by association principle, we suggest that YfgM is also part of the periplasmic chaperone network. The approach we present circumvents the need for engineering of tags and protein overexpression. It is applicable for the analysis of membrane protein complexes in any organism and will be particularly useful for less-characterized organisms where conventional strategies that require protein engineering (i.e., 2-hybrid based approaches and TAP-tagging) are not feasible.
authors.affiliation: Department of Analytical Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Maddalo
authors.forename: Filippa
authors.initials: F
authors.lastname: Stenberg-Bruzell
authors.forename: Hansjörg
authors.initials: H
authors.lastname: Götzke
authors.forename: Stephen
authors.initials: S
authors.lastname: Toddo
authors.forename: Patrik
authors.initials: P
authors.lastname: Björkholm
authors.forename: Hanna
authors.initials: H
authors.lastname: Eriksson
authors.forename: Peter
authors.initials: P
authors.lastname: Chovanec
authors.forename: Pierre
authors.initials: P
authors.lastname: Genevaux
authors.forename: Janne
authors.initials: J
authors.lastname: Lehtiö
authors.forename: Leopold L
authors.initials: LL
authors.lastname: Ilag
authors.forename: Daniel O
authors.initials: DO
authors.lastname: Daley
mesh_terms: D002852:Chromatography, Ion Exchange / Q000379:methods; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000032:analysis* / Q000145:classification / Q000302:isolation & purification; D013058:Mass Spectrometry / Q000379:methods; D008565:Membrane Proteins / Q000032:analysis* / Q000145:classification / Q000302:isolation & purification; D018832:Molecular Chaperones / Q000032:analysis* / Q000145:classification / Q000302:isolation & purification; D008970:Molecular Weight; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000302:isolation & purification; D010802:Phylogeny; D020543:Proteome / Q000032:analysis; D040901:Proteomics / Q000379:methods
chemical_list: D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D046912:Multiprotein Complexes; D020543:Proteome; C000592363:YfgM protein, E coli