Structural characterization of the fusobacterial non-specific porin FomA suggests a 14-stranded topology, unlike the classical porins.
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.
Puntervoll
Pål
P
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Ruud
Morten
M
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Bruseth
Live J
LJ
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Kleivdal
Hans
H
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Høgh
Bente T
BT
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Benz
Roland
R
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
Jensen
Harald B
HB
Department of Molecular Biology, University of Bergen, HiB, Thormøhlensgate 55, N-5020 Bergen, Norway1.
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
D001425:Bacterial Outer Membrane Proteins; D008565:Membrane Proteins; C083760:fomA protein, Fusobacterium; D014357:Trypsin