Schüler A, Bornberg-Bauer E
Evolution of Protein Domain Repeats in Metazoa
Molecular Biology and Evolution, 2016

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Repeats are ubiquitous elements of proteins and they play important roles for cellular function and during
evolution. Repeats are, however, also notoriously difficult to capture computationally and large scale studies
so far had difficulties in linking genetic causes, structural properties and evolutionary trajectories of protein
repeats. Here we apply recently developed methods for repeat detection and analysis to a large dataset
comprising over hundred metazoan genomes. We find that repeats in larger protein families experience
generally very few insertions or deletions (indels) of repeat units but there is also a significant fraction of
noteworthy volatile outliers with very high indel rates. Analysis of structural data indicates that repeats
with an open structure and independently folding units are more volatile and more likely to be intrinsically
disordered. Such disordered repeats are also significantly enriched in sites with a high functional potential
such as linear motifs. Furthermore, the most volatile repeats have a high sequence similarity between their
units. Since many volatile repeats also show signs of recombination, we conclude they are often shaped by
concerted evolution. Intriguingly, many of these conserved yet volatile repeats are involved in host-pathogen
interactions where they foster fast but subtle adaptation in biological arms races.