A1 Refereed original research article in a scientific journal
Archaic and alternative chaperones preserve pilin folding energy by providing incomplete structural information
Authors: Pakharukova N, McKenna S, Tuittila M, Paavilainen S, Malmi H, Xu Y, Parilova O, Matthews S, Zavialov AV
Publisher: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Publication year: 2018
Journal: Journal of Biological Chemistry
Journal name in source: The Journal of biological chemistry
Journal acronym: J Biol Chem
Volume: 293
Issue: 44
First page : 17070
Last page: 17080
Number of pages: 11
ISSN: 0021-9258
eISSN: 1083-351X
DOI: https://doi.org/10.1074/jbc.RA118.004170
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/36435333
Adhesive pili are external component of fibrous adhesive organelles and help bacteria attach to biotic or abiotic surfaces. The biogenesis of adhesive pili via the chaperone-usher pathway (CUP) is independent of external energy sources. In the classical CUP, chaperones transport assembly-competent pilins in a folded but expanded conformation. During donor-strand exchange, pilins subsequently collapse, producing a tightly packed hydrophobic core and releasing the necessary free energy to drive fiber formation. Here, we show that pilus biogenesis in non-classical, archaic, and alternative CUPs uses a different source of conformational energy. High-resolution structures of the archaic Csu-pili system from Acinetobacter baumannii revealed that non-classical chaperones employ a short donor strand motif that is insufficient to fully complement the pilin fold. This results in chaperone-bound pilins being trapped in a substantially unfolded intermediate. The exchange of this short motif with the longer donor strand from adjacent pilin provides the full steric information essential for folding, and thereby induces a large unfolded-to-folded conformational transition to drive assembly. Our findings may inform the development of anti-adhesion drugs (pilicides) to combat bacterial infections.
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