Formation of a gated channel by a ligand-specific transport protein in the bacterial outer membrane.
The ferric enterobactin receptor (FepA) is a high-affinity ligand-specific transport protein in the outer membrane of Gram-negative bacteria. Deletion of the cell-surface ligand-binding peptides of FepA generated mutant proteins that were incapable of high-affinity uptake but that instead formed nonspecific, passive channels in the outer membrane. Unlike native FepA, these pores acted independently of the accessory protein TonB, which suggests that FepA is a gated porin and that TonB acts as its gatekeeper by facilitating the entry of ligands into the FepA channel. The sequence homology among TonB-dependent proteins suggests that all ligand-specific outer membrane receptors may function by this gated-porin mechanism.
Rutz
J M
JM
Department of Microbiology, Medical College of Wisconsin, Milwaukee 53226.
Liu
J
J
Lyons
J A
JA
Goranson
J
J
Armstrong
S K
SK
McIntosh
M A
MA
Feix
J B
JB
Klebba
P E
PE
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry; D000954:Antigens, Surface / Q000737:chemistry; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*; D002352:Carrier Proteins / Q000276:immunology / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004758:Enterobactin / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015640:Ion Channel Gating; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D011956:Receptors, Cell Surface; D013329:Structure-Activity Relationship
D000942:Antigens, Bacterial; D000954:Antigens, Surface; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D011956:Receptors, Cell Surface; C029489:enterobactin receptor; D004758:Enterobactin