title: Structural characterization of the fusobacterial non-specific porin FomA suggests a 14-stranded topology, unlike the classical porins.
abstract: Native and recombinant FomA proteins were extracted by detergent from the cell envelopes of Fusobacterium nucleatum and Escherichia coli, and purified to near homogeneity by chromatography. Circular dichroism analysis revealed that the FomA protein consists predominantly of beta-sheets, in line with the previously proposed 16-stranded beta-barrel topology model. Results obtained by trypsin treatment of intact cells and cell envelopes of F. nucleatum, and from limited proteolysis of purified FomA protein, indicated that the N-terminal part of the FomA protein is not an integral part of the beta-barrel, but forms a periplasmic domain. Based on these results a new topology model is proposed for the FomA protein, where the C-terminal part forms a 14-stranded beta-barrel separate from the periplasmic N-terminal domain.
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Pål
authors.initials: P
authors.lastname: Puntervoll
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Morten
authors.initials: M
authors.lastname: Ruud
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Live J
authors.initials: LJ
authors.lastname: Bruseth
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Hans
authors.initials: H
authors.lastname: Kleivdal
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Bente T
authors.initials: BT
authors.lastname: Høgh
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Roland
authors.initials: R
authors.lastname: Benz
authors.affiliation: Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
authors.forename: Harald B
authors.initials: HB
authors.lastname: Jensen
mesh_terms: D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000302:isolation & purification; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry; D016967:Fusobacterium nucleatum / Q000737:chemistry*; D008565:Membrane Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D014357:Trypsin / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D008565:Membrane Proteins; C083760:fomA protein, Fusobacterium; D014357:Trypsin