title: Outer-membrane PapC molecular usher discriminately recognizes periplasmic chaperone-pilus subunit complexes.
abstract: P pili are highly ordered composite structures consisting of thin fibrillar tips joined end-to-end to rigid helical rods. The production of these virulence-associated structures requires a periplasmic chaperone (PapD) and an outer membrane protein (PapC) that is the prototype member of a newly recognized class of proteins that we have named "molecular ushers." Two in vitro assays showed that the preassembly complexes that PapD forms with the three most distal tip fibrillar proteins (PapG, PapF, and PapE) bound to PapC. The relative affinity of each complex for PapC was found to correlate with the final position of the subunit type in the tip fibrillum. In contrast, the complexes PapD forms with the major component of the pilus rod, PapA, or the pilus rod initiating protein, PapK, did not recognize PapC. The in vitro data argue that differential targeting of chaperone-subunit complexes to PapC may be part of a mechanism to ensure the correctly ordered assembly of adhesive composite pili.
authors.affiliation: Washington University Medical School, Department of Molecular Microbiology, St. Louis, MO 63110.
authors.forename: K W
authors.initials: KW
authors.lastname: Dodson
authors.forename: F
authors.initials: F
authors.lastname: Jacob-Dubuisson
authors.forename: R T
authors.initials: RT
authors.lastname: Striker
authors.forename: S J
authors.initials: SJ
authors.lastname: Hultgren
mesh_terms: D018830:Adhesins, Escherichia coli; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002846:Chromatography, Affinity; D002852:Chromatography, Ion Exchange; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D015870:Gene Expression; D005838:Genotype; D007700:Kinetics; D046911:Macromolecular Substances; D008954:Models, Biological; D008969:Molecular Sequence Data; D010957:Plasmids
chemical_list: D018830:Adhesins, Escherichia coli; D001425:Bacterial Outer Membrane Proteins; D046911:Macromolecular Substances