Imperfect repeats in the functional amyloid protein FapC reduce the tendency to fragment during fibrillation

ABSTRACT Functional amyloid (FA) is widespread in bacteria and serves multiple purposes such as strengthening of biofilm and contact with eukaryotic hosts. Unlike pathological amyloid, FA has been subjected to evolutionary optimization which is likely to be reflected in the aggregation mechanism. FA...

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Bibliographic Details
Published in:Protein science 2019-03, Vol.28 (3), p.633-642
Main Authors: Rasmussen, Casper B., Christiansen, Gunna, Vad, Brian S., Lynggaard, Carina, Enghild, Jan J., Andreasen, Maria, Otzen, Daniel
Format: Article
Language:English
Subjects:
Agglomeration
aggregation mechanisms
Amino Acid Sequence
Amylofit
Amyloid - chemistry
Amyloid - ultrastructure
Amyloidogenic Proteins - chemistry
Bacteria
Biofilms
E coli
FapC
Fibrillation
Fibrils
Full‐Length Paper
Full‐Length Papers
Humans
kinetic analysis
Kinetics
Models, Molecular
Modular design
Protein Aggregates
Proteins
Pseudomonas - chemistry
Pseudomonas Infections - microbiology
Thioflavin T
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Summary:ABSTRACT Functional amyloid (FA) is widespread in bacteria and serves multiple purposes such as strengthening of biofilm and contact with eukaryotic hosts. Unlike pathological amyloid, FA has been subjected to evolutionary optimization which is likely to be reflected in the aggregation mechanism. FA from different bacteria, including Escherichia coli (CsgA) and Pseudomonas (FapC), contains a number of imperfect repeats which may be key to efficient aggregation. Here we report on the aggregative behavior of FapC constructs which represent all single, double, and triple deletions of the protein's three imperfect repeats. Analysis of the fibrillation kinetics by the program Amylofit reveals that the removal of these repeats increases the tendency of the growing fibrils to fragment and also generally increases aggregation half‐times. Remarkably, even the mutant lacking all three repeats was able to fibrillate, although fibrillation was much more irregular and led to significantly altered and destabilized fibrils. We conclude that imperfect repeats can promote fibrillation efficiency thanks to their modular design, though the context of the imperfect repeats also plays a significant role.
ISSN:0961-8368
1469-896X
DOI:10.1002/pro.3566