Structural basis of chaperone self-capping in P pilus biogenesis.
Hung, D.L., Pinkner, J.S., Knight, S.D., Hultgren, S.J.(1999) Proc Natl Acad Sci U S A 96: 8178-8183
- PubMed: 10393968 
- DOI: https://doi.org/10.1073/pnas.96.14.8178
- Primary Citation of Related Structures:  
1QPP, 1QPX - PubMed Abstract: 
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.
Organizational Affiliation: 
Department of Molecular Microbiology, Box 8230, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.