title: Proteomic screening and identification of differentially distributed membrane proteins in Escherichia coli.
abstract: Bacteria show asymmetric subcellular distribution of many proteins involved in diverse cellular processes such as chemotaxis, motility, actin polymerization, chromosome partitioning and cell division. In many cases, the specific subcellular localization of these proteins is critical for proper regulation and function. Although cellular organization of the bacterial cell clearly plays an important role in cell physiology, systematic studies to uncover asymmetrically distributed proteins have not been reported previously. In this study, we undertook a proteomics approach to uncover polar membrane proteins in Escherichia coli. We identified membrane proteins enriched in E. coli minicells using a combination of two-dimensional electrophoresis and mass spectrometry. Among a total of 173 membrane protein spots that were consistently detected, 36 spots were enriched in minicell membranes, whereas 15 spots were more abundant in rod cell membranes. The minicell-enriched proteins included the inner membrane proteins MCPs, AtpA, AtpB, YiaF and AcrA, the membrane-associated FtsZ protein and the outer membrane proteins YbhC, OmpW, Tsx, Pal, FadL, OmpT and BtuB. We immunolocalized two of the minicell-enriched proteins, OmpW and YiaF, and showed that OmpW is a bona fide polar protein whereas YiaF displays a patchy membrane distribution with a polar and septal bias.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University, Ann Arbor, MI 48109, USA.
authors.forename: Erh-Min
authors.initials: EM
authors.lastname: Lai
authors.forename: Usha
authors.initials: U
authors.lastname: Nair
authors.forename: Nikhil D
authors.initials: ND
authors.lastname: Phadke
authors.forename: Janine R
authors.initials: JR
authors.lastname: Maddock
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000032:analysis; D001426:Bacterial Proteins; D002628:Chemoreceptor Cells / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000032:analysis*; D050612:Fatty Acid Transport Proteins; D036781:Fimbriae Proteins; D008074:Lipoproteins / Q000032:analysis; D013058:Mass Spectrometry; D008565:Membrane Proteins / Q000032:analysis*; D026901:Membrane Transport Proteins; D008856:Microscopy, Fluorescence; D010447:Peptide Hydrolases; D010457:Peptidoglycan / Q000032:analysis; D018272:Porins / Q000032:analysis; D020543:Proteome; D018000:Receptors, Peptide / Q000032:analysis; D011991:Receptors, Virus / Q000032:analysis
chemical_list: C083497:AcrA protein, E coli; C078802:AtpA protein, E coli; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C044592:BtuB protein, E coli; D029968:Escherichia coli Proteins; C031163:ExcC protein, E coli; D050612:Fatty Acid Transport Proteins; C076835:FtsZ84 protein, E coli; D008074:Lipoproteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; D010457:Peptidoglycan; D018272:Porins; D020543:Proteome; D018000:Receptors, Peptide; D011991:Receptors, Virus; C065691:fadL protein, E coli; C499588:ompT protein, E coli; C064035:ompW protein, E coli; C066743:Tsx protein, E coli; D036781:Fimbriae Proteins; D010447:Peptide Hydrolases