Characterization of FimC, a periplasmic assembly factor for biogenesis of type 1 pili in Escherichia coli.
Assembly of type 1 pili from Escherichia coli is mediated by FimC, a periplasmic chaperone (assembly factor) consisting of two immunoglobulin-like domains. FimC is assumed to recognize the individual pilus subunits in the periplasm mainly via their conserved C-terminal segments and to deliver the subunits to an assembly platform in the outer membrane. Here we present the first biochemical characterization of a periplasmic pilus chaperone and analyze the importance of the two chaperone domains for stability and function. Comparison of the isolated C-terminal domain with wild-type FimC revealed a strongly reduced thermodynamic stability, indicating strong interdomain interactions. The affinity of FimC toward a peptide corresponding to the 11 C-terminal residues of the type 1 pilus adhesin FimH is at least 1000-fold lower compared to binding of intact FimH, confirming that bacterial pilus chaperones, unlike other chaperones, specifically interact with folded pilus subunits.
Hermanns
U
U
Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule Hönggerberg, CH-8093 Zürich, Switzerland.
Sebbel
P
P
Eggli
V
V
Glockshuber
R
R
D018829:Adhesins, Bacterial / Q000378:metabolism; D018830:Adhesins, Escherichia coli; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001426:Bacterial Proteins; D002942:Circular Dichroism; D004926:Escherichia coli / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins; D010861:Fimbriae, Bacterial / Q000737:chemistry / Q000378:metabolism*; D018832:Molecular Chaperones / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D019897:Periplasm / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017510:Protein Folding; D017434:Protein Structure, Tertiary / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
D018829:Adhesins, Bacterial; D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments; D011994:Recombinant Proteins; C489721:fimC protein, E coli; C058769:fimH protein, E coli; D036781:Fimbriae Proteins