FimC is a periplasmic PapD-like chaperone that directs assembly of type 1 pili in bacteria.
Biogenesis of the type 1 pilus fiber in Escherichia coli requires the product of the fimC locus. We have demonstrated that FimC is a member of the periplasmic chaperone family. The deduced primary sequence of FimC shows a high degree of homology to PapD and fits well with the derived consensus sequence for periplasmic chaperones, predicting that it has an immunoglobulin-like topology. The chaperone activity of FimC was demonstrated by purifying a complex that FimC forms with the FimH adhesion. A fimC1 null allele could be complemented by the prototype member of the chaperone superfamily, PapD, resulting in the production of adhesive type 1 pili. The general mechanism of action of members of the chaperone superfamily was demonstrated by showing that the ability of PapD to assemble both P and type 1 pili was dependent on an invariant arginine residue (Arg-8), which forms part of a conserved subunit binding site in the cleft of PapD. We suggest that the conserved cleft is a subunit binding feature of all members of this protein family. These studies point out the general strategies used by Gram-negative bacteria to assemble adhesins into pilus fibers, allowing them to promote attachment to eukaryotic receptors.
Jones
C H
CH
Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110.
Pinkner
J S
JS
Nicholes
A V
AV
Slonim
L N
LN
Abraham
S N
SN
Hultgren
S J
SJ
D018830:Adhesins, Escherichia coli; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000502:physiology*; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006386:Hemagglutination Tests; D006388:Hemagglutinins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid
D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D006388:Hemagglutinins; C489721:fimC protein, E coli; D036781:Fimbriae Proteins