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Chaperones mainly suppress primary nucleation during formation of functional amyloid required for bacterial biofilm formation

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DOI

  • Madhu Nagaraj
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  • Zahra Najarzadeh
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  • Jonathan Pansieri, Umeå University
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  • Henrik Biverstål, Karolinska Institutet
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  • Greta Musteikyte, Vilnius University Hospital Santariškių Klinikos, Vilnius, Lithuania; Clinic of Children's Diseases, Medical Faculty, Vilnius University, Vilnius, Lithuania.
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  • Vytautas Smirnovas, Vilnius University Hospital Santariškių Klinikos, Vilnius, Lithuania; Clinic of Children's Diseases, Medical Faculty, Vilnius University, Vilnius, Lithuania.
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  • Steve Matthews, Imperial College London
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  • Cecilia Emanuelsson, Center for Molecular Protein Science
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  • Janne Johansson, Department of Biosciences and Nutrition, Karolinska Institute, Stockholm, Sweden
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  • Joel N Buxbaum, The Scripps Research Institute 10550 North Torrey Pines Road La Jolla CA 92037 USA.
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  • Ludmilla Morozova-Roche, Division of Biochemistry, Department of Medical Biochemistry and Biophysics
  • ,
  • Daniel E Otzen

Unlike misfolding in neurodegenerative diseases, aggregation of functional amyloids involved in bacterial biofilm, e.g. CsgA (E. coli) and FapC (Pseudomonas), is carefully regulated. However, it is unclear whether functional aggregation is inhibited by chaperones targeting pathological misfolding and if so by what mechanism. Here we analyze how four entirely different human chaperones or protein modulators (transthyretin, S100A9, Bri2 BRICHOS and DNAJB6) and bacterial CsgC affect CsgA and FapC fibrillation. CsgA is more susceptible to inhibition than FapC and the chaperones vary considerably in the efficiency of their inhibition. However, mechanistic analysis reveals that all predominantly target primary nucleation rather than elongation or secondary nucleation, while stoichiometric considerations suggest that DNAJB6 and CsgC target nuclei rather than monomers. Inhibition efficiency broadly scales with the chaperones' affinity for monomeric CsgA and FapC. The chaperones tend to target the most aggregation-prone regions of CsgA, but do not display such tendencies towards the more complex FapC sequence. Importantly, the most efficient inhibitors (Bri2 BRICHOS and DNAJB6) significantly reduce bacterial biofilm formation. This commonality of chaperone action may reflect the simplicity of functional amyloid formation, driven largely by primary nucleation, as well as the ability of non-bacterial chaperones to deploy their proteostatic capacities across biological kingdoms.

Original languageEnglish
JournalChemical Science
Volume13
Issue2
Pages (from-to)536-553
Number of pages18
ISSN2041-6520
DOIs
Publication statusPublished - Jan 2022

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