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.
Hung
D L
DL
Department of Molecular Microbiology, Box 8230, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
Pinkner
J S
JS
Knight
S D
SD
Hultgren
S J
SJ
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