Resolving the energy paradox of chaperone/usher-mediated fibre assembly
2005 (English)In: Biochemical Journal, ISSN 0264-6021, E-ISSN 1470-8728, Vol. 389, no Pt 3, 685-694 p.Article in journal (Refereed) Published
Periplasmic chaperone/usher machineries are used for assembly of filamentous adhesion organelles of Gram-negative pathogens in a process that has been suggested to be driven by folding energy. Structures of mutant chaperone–subunit complexes revealed a final folding transition (condensation of the subunit hydrophobic core) on the release of organelle subunit from the chaperone–subunit pre-assembly complex and incorporation into the final fibre structure. However, in view of the large interface between chaperone and subunit in the pre-assembly complex and the reported stability of this complex, it is difficult to understand how final folding could release sufficient energy to drive assembly. In the present paper, we show the X-ray structure for a native chaperone–fibre complex that, together with thermodynamic data, shows that the final folding step is indeed an essential component of the assembly process. We show that completion of the hydrophobic core and incorporation into the fibre results in an exceptionally stable module, whereas the chaperone–subunit pre-assembly complex is greatly destabilized by the high-energy conformation of the bound subunit. This difference in stabilities creates a free energy potential that drives fibre formation.
Place, publisher, year, edition, pages
2005. Vol. 389, no Pt 3, 685-694 p.
Bacterial Proteins/*chemistry/*physiology, Models; Molecular, Molecular Chaperones/*chemistry/*physiology, Organelles/chemistry, Protein Conformation, Protein Folding, Protein Subunits, Research Support; Non-U.S. Gov't, Thermodynamics
IdentifiersURN: urn:nbn:se:uu:diva-77571PubMedID: 15799718OAI: oai:DiVA.org:uu-77571DiVA: diva2:105483