Premium
Imperfect repeats in the functional amyloid protein FapC reduce the tendency to fragment during fibrillation
Author(s) -
Rasmussen Casper B.,
Christiansen Gunna,
Vad Brian S.,
Lynggaard Carina,
Enghild Jan J.,
Andreasen Maria,
Otzen Daniel
Publication year - 2019
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.3566
Subject(s) - amyloid (mycology) , context (archaeology) , escherichia coli , fibrillation , protein aggregation , biology , genetics , biophysics , chemistry , gene , medicine , paleontology , botany , cardiology , atrial 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 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.