Repeat-containing effectors of filamentous pathogens and symbionts

Pathogenic and symbiotic filamentous microbes secrete effectors which suppress host immune responses and promote a successful colonization. Pathogen effectors are engaged in the arms race with their hosts and because of this they are subject to intense evolutionary pressure. Effectors particularly prone to rapid evolution display repeat-containing domains which can easily expand or contract and accumulate point mutations without altering their original function. In this review we address the diversity of function in such repeat-containing effectors, focus on new findings and point out avenues for future work.