Structural basis of chaperone self-capping in P pilus biogenesis.
PapD is an immunoglobulin-like chaperone that mediates the assembly of P pili in uropathogenic strains of Escherichia coli. It binds and caps interactive surfaces on pilus subunits to prevent their premature associations in the periplasm. We elucidated the structural basis of a mechanism whereby PapD also interacts with itself, capping its own subunit binding surface. Crystal structures of dimeric forms of PapD revealed that this self-capping mechanism involves a rearrangement and ordering of the C2-D2 and F1-G1 loops upon dimerization which might ensure that a stable dimer is not formed in solution in spite of a relatively large dimer interface. An analysis of site directed mutations revealed that chaperone dimerization requires the same surface that is otherwise used to bind subunits.
Department of Molecular Microbiology, Box 8230, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
D L
DL
Hung
J S
JS
Pinkner
S D
SD
Knight
S J
SJ
Hultgren
D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003196:Computer Graphics; D018360:Crystallography, X-Ray; D019281:Dimerization; D004926:Escherichia coli / Q000502:physiology*; D029968:Escherichia coli Proteins; D010861:Fimbriae, Bacterial / Q000235:genetics / Q000502:physiology*; D007700:Kinetics; D046911:Macromolecular Substances; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D033903:Periplasmic Proteins; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D018832:Molecular Chaperones; C084330:PapD protein, E coli; D033903:Periplasmic Proteins; D011994:Recombinant Proteins